Meaning - GMAT Verbal

In your initial scan of the answer choices, the only difference you will probably notice quickly is that between “is” and “develops” in "A crippling disorder for many young women, anorexia nervosa is", "A crippling disorder that affects many young women, anorexia nervosa is", and "A crippling disorder for many young women, anorexia nervosa develops". Why would you be given such a difference? Look at what follows the verb and you see that "A crippling disorder for many young women, anorexia nervosa is" and "A crippling disorder that affects many young women, anorexia nervosa is" suffer from illogical predication – the subject “anorexia nervosa” is illogically linked by the verb “is” to a clause starting with “when”. An illness or disorder is not a timeframe! The verb “develops” works because the clause then explains when/how the illness develops so "A crippling disorder for many young women, anorexia nervosa develops" is correct. In "Anorexia nervosa is a crippling disorder for many young women,", you again have the problem of what the “when” clause is linked to – there is no action verb like “develops” that can be modified by the clause. For "Anorexia nervosa is a crippling disorder for many young women;" you have an improper use of a semicolon as the clause that follows is not an independent sentence.

This sentence contains a tricky sentence construction issue that you will likely miss unless you “Slash and Burn” the unnecessary parts of the sentence. The sentence is trying to show that there are two things relating to the 1000 patients: patients “whose cardiac disease was not well controlled….and who had not suffered persistent symptoms”. In "and had suffered persistent symptoms that had been lasting for at least a year", "and suffered from persistent symptoms that had lasted for at least a year", "but were suffering from persistent symptoms that had been lasting for a year or more" and "but had suffered from persistent symptoms that lasted for a year or more" the verb forms following the dash are illogically referring back to cardiac disease. Take "and suffered from persistent symptoms that had lasted for at least a year" for instance - without the “and who” it reads like this: “patients whose cardiac disease was not well controlled and suffered…” The suffered is not referring back to patients but is necessarily part of the “whose” clause and is commanded illogically by “cardiac disease”. Only "and who suffered persistent symptoms that had been lasting for at least a year" corrects this issue - that choice should be a major “decision points” hint to carefully analyze why the “who” might be required in this sentence. Answer is "and who suffered persistent symptoms that had been lasting for at least a year".

This problem is primarily testing logical meaning, pronoun reference, and sentence construction. Whenever you have a pronoun choice in the answers, start there: "trying to save their crops when they are foraging for late-night snacks, or by poachers" and "who are trying to save their crops when they are foraging for late-night snacks, or by poachers who are" use the pronoun “they” while the remaining choices use “animals”. This is a major hint that the pronoun “they” might have a reference problem and indeed it does: it is not the farmers who are “foraging for late-night snacks” but rather the giraffes! The use of the word “animals” corrects this problem so it must be "trying to save their crops when the animals are foraging for late-night snacks or poachers", "trying to save their crops when the animals are foraging for late-night snacks, or by poachers" or "who are trying to save their crops when the animals are foraging for late-night snacks or poachers who are".

The most obvious decision point between the remaining choices is the use of “or poachers” in "trying to save their crops when the animals are foraging for late-night snacks or poachers" and "who are trying to save their crops when the animals are foraging for late-night snacks or poachers who are" versus “or by poachers” in "trying to save their crops when the animals are foraging for late-night snacks, or by poachers". A closer look (and the use of slash-and-burn to simplify the sentence) shows that it should be: the giraffes have been shot by farmers doing X, or BY poachers doing Y. Without the word “by”, it seems that the last part is linked to what the animals are doing when it is really a separate component going back to who is shooting the giraffes. If you read "trying to save their crops when the animals are foraging for late-night snacks or poachers" and "who are trying to save their crops when the animals are foraging for late-night snacks or poachers who are" carefully it seems that the giraffes might be foraging for poachers – clearly illogical! The correct answer is "trying to save their crops when the animals are foraging for late-night snacks, or by poachers".

The most important decision point in this problem relates to the sometimes subtle error of "illogical predication" - when the subject is not logically linked to what follows. Before you get to that, you can quickly eliminate as "requiring that condominium associations receive at least 80 percent of their gross income from their tenant-shareholders, and have no more than 20 percent from other sources, such as" there is no active verb - “requiring” is just a participle. In "required condominium associations to receive at least 80 percent of their gross income from their tenant-shareholders, and have no more than 20 percent from other sources, such as", "required that condominium associations receive at least 80 percent of their gross income from their tenant-shareholders, and have no more than 20 percent from other sources, such as", and "required condominium associations to receive at least 80 percent of their gross income from their tenant-shareholders, and to have no more than 20 percent from other sources, like" “have no more…” is incorrect: you do not “have 20% of your income from other sources” you “receive 20% of your income from other sources”. Only "required that condominium associations receive at least 80 percent of their gross income from their tenant-shareholders, and no more than 20 percent from other sources, such as" gets the predication correct: “require that associations receive at least 80% from this…, and no more than 20% from other sources” The comma confuses some students but it is there to make it clear that the first part ends after “from shareholders.” The sentence is really “receive at least 80% from this and no more than 20% from this…”. Answer is "required that condominium associations receive at least 80 percent of their gross income from their tenant-shareholders, and no more than 20 percent from other sources, such as".

With only one concrete decision point (the verb choice and what follows), you need to figure out what is really going on in the sentence. Often this is best done by using “slash-and-burn” to eliminate any garbage and only read the core elements. The last part of the sentence in "may be" is really “the damage…may be public health and safety.” This is clearly illogical predication! Public health and safety are not “damage”.

Leveraging the fact that "had been to" and "may be to" have the necessary “to” at the end, you can see that "may be to" is correct: “the damage…may be TO public health and safety.” You can have damage TO public health and safety - this option makes sense. "had been to" – the only other answer with the necessary “to” – is incorrect as the past perfect tense “had been” cannot be used with present perfect “has been” used earlier in the sentence. Correct answer is "may be to".

The end of this sentence needs to logically convey whether computer technology can power economic growth in the same way that the steam engine and the printing press used to power economic growth when they were important. "whether computer technology can power economic growth like the steam engine and the printing press", "whether technology can power economic growth as the steam engine and the printing press do", and "if computer technology can power economic growth as the steam engine and the internal combustion engine of the past do" all compare computer technology to the PRESENT impact of the steam engine and the printing press on economic growth – clearly illogical as those have no impact today on economic growth today. "whether computer technology can power economic growth the way the steam engine and the printing press did" and "if computer technology can power economic growth like the way the steam engine and the printing press did" make the proper comparison between computer technology today and the steam engine and printing press in the past. "if computer technology can power economic growth like the way the steam engine and the printing press did" is wrong, however, because of the redundant and incorrect structure “like the way” and the incorrect conditional “if” that starts the clause. "whether computer technology can power economic growth the way the steam engine and the printing press did" uses the correct “whether” and makes a logical and proper comparison.

This problem features several subtle meaning-related errors, errors that are much easier to spot and understand if you use good Decision Points strategy to identify the major differences between answer choices.

Note first that choices "the approval ratings among his constituents and the stock market dropping rapidly, the president announced a series of spending initiatives to try stimulating"/"the approval ratings among his constituents and the stock market dropping rapidly, the president announced a series of spending initiatives trying to stimulate" and "the stock market and the approval ratings among his constituents dropping rapidly, the president announced a series of spending initiatives to try and stimulate"/"the stock market and with the approval ratings among his constituents dropping rapidly, the president announced a series of spending initiatives that will try to stimulate"/"the stock market and the approval ratings among his constituents dropping rapidly, the president announced a series of spending initiatives to try to stimulate" flip the order of "the approval ratings" and "the stock market." Is that important? In "the approval ratings among his constituents and the stock market dropping rapidly, the president announced a series of spending initiatives to try stimulating" and "the approval ratings among his constituents and the stock market dropping rapidly, the president announced a series of spending initiatives trying to stimulate", "the approval ratings among" applies to both nouns that follow it ("his constituents and the stock market"), creating an illogical meaning: the stock market doesn't give approval ratings! By changing that order and putting the stock market first, "the stock market and the approval ratings among his constituents dropping rapidly, the president announced a series of spending initiatives to try and stimulate", "the stock market and with the approval ratings among his constituents dropping rapidly, the president announced a series of spending initiatives that will try to stimulate", and "the stock market and the approval ratings among his constituents dropping rapidly, the president announced a series of spending initiatives to try to stimulate" fix that error, keeping "the approval ratings among" separate and applicable only to "his constituents."

In choice "the approval ratings among his constituents and the stock market dropping rapidly, the president announced a series of spending initiatives trying to stimulate", the phrase " the president announced a series of spending initiatives trying to stimulate" assigns the verb "trying" to the spending initiatives. But that's not logical either - initiatives are inanimate and can't "try" to do anything; it's the president trying to stimulate the economy, not the initiatives. So "the approval ratings among his constituents and the stock market dropping rapidly, the president announced a series of spending initiatives trying to stimulate" is also incorrect for a meaning reason.

"the stock market and with the approval ratings among his constituents dropping rapidly, the president announced a series of spending initiatives that will try to stimulate" makes a very similar meaning error: by saying "spending initiatives that will try to stimulate" this choice makes it seem again like the initiatives will try, and that just cannot be true.

Between "the stock market and the approval ratings among his constituents dropping rapidly, the president announced a series of spending initiatives to try and stimulate" and "the stock market and the approval ratings among his constituents dropping rapidly, the president announced a series of spending initiatives to try to stimulate", there is a one-word difference: "the stock market and the approval ratings among his constituents dropping rapidly, the president announced a series of spending initiatives to try and stimulate" has "try and stimulate" while "the stock market and the approval ratings among his constituents dropping rapidly, the president announced a series of spending initiatives to try to stimulate" has "try to stimulate." While in common speech you may be accustomed to hearing the two used interchangeably, the "and" creates a totally different meaning - by linking two parallel verbs ("try" and "stimulate"), "and" creates the meaning that those two actions are independent. That's an incorrect meaning: "stimulate" is exactly what the president is trying to do. "Try to stimulate" conveys that meaning properly, making answer choice "the stock market and the approval ratings among his constituents dropping rapidly, the president announced a series of spending initiatives to try to stimulate" correct.

In analyzing the decision points between the five answer choices, you should first notice the difference between “in ascribing” in "in ascribing these ailments to a psychological disorder", "in ascribing a psychological disorder as the cause for these ailments", and "in ascribing a psychological disorder to these ailments" and "if these ailments are ascribed" in "if these ailments are ascribed as the cause for a psychological disorder" and "if these ailments are ascribed to a psychological disorder". Additionally, you should see that "if these ailments are ascribed as the cause for a psychological disorder" and "in ascribing a psychological disorder as the cause for these ailments" contain the words “as a cause” while the other choices do not. Probably the easiest of those decision points to assess is the addition of “as a cause”. The word "ascribe" already means "to credit or assign, as to a cause or source" so "if these ailments are ascribed as the cause for a psychological disorder" and "in ascribing a psychological disorder as the cause for these ailments" are redundant. For "in ascribing these ailments to a psychological disorder" and "in ascribing a psychological disorder to these ailments" the use of the modifying phrase “in ascribing” illogically modifies the patients, suggesting that the patients are the ones doing the ascribing. Clearly, it is the doctor who is doing the ascribing and the “if” clause, which does not then modify the patients, makes the meaning logical. Correct answer is "if these ailments are ascribed to a psychological disorder".

This problem (like many others) tests logical meaning. Note the use of the word "other" in choices "As some of the busiest airports and ports in Europe, the United Kingdom has far more invasive species of certain types than does any other European country." and "With some of the busiest airports and ports in Europe, the United Kingdom has far more invasive species of certain types than does any other European country.", and compare that to the usage in "With some of the busiest airports and ports in Europe, the United Kingdom has far more invasive species of certain types than does any European country."/"Because of some of the busiest airports and ports in Europe, the United Kingdom has far more invasive species of certain types than does any European country."/"Because it has some of the busiest airports and ports in Europe, the United Kingdom has far more invasive species of certain types than any European country does.". Can the UK have more invasive species than any European country, when it is a European country itself? Logically, no - it can have the most of any country in Europe, but not more than any country. The best it can do is "tie" itself. So this sentence requires the use of "other" to be logically correct.

Then notice the major difference between "As some of the busiest airports and ports in Europe, the United Kingdom has far more invasive species of certain types than does any other European country." and "With some of the busiest airports and ports in Europe, the United Kingdom has far more invasive species of certain types than does any other European country.". The UK has some of the busiest (air)ports, but it is not itself the busiest airports and ports. So "As some of the busiest airports and ports in Europe, the United Kingdom has far more invasive species of certain types than does any other European country." is illogical, meaning that "With some of the busiest airports and ports in Europe, the United Kingdom has far more invasive species of certain types than does any other European country." must be the correct answer.

This problem provides two very clear decision points for you to get started:

1. "they" vs. "it" as the first word of the sentence

2. "that of" vs. "those of" vs. (no possessive) in relation to "the Medieval period"

The key to both of these is recognizing the subject of the sentence which is "global temperatures." Since temperatures is plural, the pronoun that corresponds to them must be "they" and you can eliminate choices "it has only recently eclipsed the Medieval period, during which, scientists theorize, a" and "it has only recently eclipsed that of the Medieval period, during which scientists theorize a".

Then notice that the comparison is between current global temperatures and the temperatures during the Medieval period; you cannot logically compare "temperatures" with the timeframe, so you need to have "those of" (which "they have only recently eclipsed those of the Medieval period, during which scientists theorize that a" and "it has only recently eclipsed that of the Medieval period, during which scientists theorize a" have but "they have only recently eclipsed the Medieval period, during which scientists theorize that a" does not) to properly draw the comparison.

Between "they have only recently eclipsed those of the Medieval period, during which scientists theorize that a" and "they have only recently eclipsed those of the Medieval period, during which, scientists theorize, a", notice that the only difference is commas around "during which." Why is that important? Here you're dealing with a tense/timeline decision. Since "theorize" is present-tense but the Medieval period is clearly in the past (even if you're not a historian, the fixed past tense "sent" outside the underline tells you that those volcanoes were in the past), you cannot have "scientists theorize" as part of the phrase "during which." The scientists currently theorize that volcanoes caused the global warming, so you need to separate that subject-verb from the modifier "during (the Medieval period)." This means that answer choice "they have only recently eclipsed those of the Medieval period, during which, scientists theorize, a" is correct.

In this sentence correction problem, it is very easy to access the decision points because there is only one word underlined! So the difference between those five choices to start the sentence obviously matters and you need to figure out why.

To do this you must look at the entire sentence - a classic example of the “Whole Sentence Matters” device used by testmakers. The primary issue is which of these modifiers creates logical meaning with the rest of the sentence. Clearly, the phrase must modify “rainforests”- and do rainforests “have” or “possess” a portion of the earth’s surface? Or do they just represent it? They simply are that portion of the earth’s surface, so only “as” "being" and “although accounting for” could be correct choices. Answer choices "With" and "Despite having" illogically suggest that rainforests have or are with 7% of the world's surface areas.

For the choice between "As", "Being" and "Although accounting for", the decision comes down to the meaning of the sentence. The rest of the sentence goes on to talk about what a large impact the rainforest have on the planet, but the introductory phrase talks about how rainforests are (only) 7% of the earth’s surface. Answer choices "As" and "Being" illogically suggest that the reason they have such a large impact is because they are such a small percentage of the earth's surface area! With that in mind, you see that the sentence requires a transition to set up a logical meaning – although rainforests represent a small area, they have a huge impact. Therefore, the phrase “although accounting for” is necessary, and the correct answer is "Although accounting for".

The only decision points in this problem are the choice between "and" and "or" at the end of the series and the choice in how the series are constructed. Each one of these separate things - genetic engineering, ionizing radiation, and sewage sludge - is something that if true would prevent anything from being labeled organic. You do not need all three to be disqualified from being labeled organic so the word "and" is incorrect - it must be "or". Similarly the words "as well as" in "genetic engineering or ionizing radiation, as well as the use of sewage sludge," create the same problem so you can eliminate "genetic engineering or ionizing radiation, and with sewage sludge,", "genetic engineering or ionizing radiation, as well as the use of sewage sludge,", and "genetic engineering, ionizing radiation, and sewage sludge" for this reason. "genetic engineering or ionizing radiation, or the use of sewage sludge," is a fairly easy-to-recognize error of parallelism in the series so correct answer is "genetic engineering, ionizing radiation, or sewage sludge".

"supermoon, which is the full or new moon that occurs when the moon is at or near its closest approach to the Earth, and which can make the moon appear" contains a sentence construction error: the subject "supermoon" never gets a verb, so we are left with a fragment. "supermoon is the full or new moon that occurs when the moon is at or near its closest approach to the Earth and can make the moon appear" suggests either that "a supermoon" can make the moon appear larger or that "the moon" can make the moon appear larger, but neither of these construals is acceptable, since a supermoon is the moon and one would never say that "the moon makes the moon appear larger." "supermoon is the full or new moon that occurs when the moon is at or near its closest approach to the Earth and appears" correctly suggests either that "a supermoon" appears much larger than the moon typically does or that "the moon" appears much larger than the moon typically does. In "supermoon is the full or new moon that occurs when the moon is at or near its closest approach to the Earth, a position which causes itself to appear", the phrase "causes itself" does not work logically, since the position does not make itself appear larger. "supermoon, which is the full or new moon that occurs when the moon is at or near its closest approach to the Earth, causes the moon to appear" suggests that the "supermoon" causes the moon to appear larger, but that claim is illogical, since the "supermoon" is the moon. Note: "supermoon is the full or new moon that occurs when the moon is at or near its closest approach to the Earth and can make the moon appear" and "supermoon is the full or new moon that occurs when the moon is at or near its closest approach to the Earth and appears are both characterized by the same flexible/fuzzy subject-verb relationships. In "supermoon is the full or new moon that occurs when the moon is at or near its closest approach to the Earth and can make the moon appear", either "a supermoon" or "the moon" (first instance) could be legitimately posited as the subject of "can make"; in "supermoon is the full or new moon that occurs when the moon is at or near its closest approach to the Earth and appears", either "a supermoon" or "the moon" (first instance) could be legitimately posited as the subject of "appears." What's important is that whichever construct one favors, the reasoning above holds: "supermoon is the full or new moon that occurs when the moon is at or near its closest approach to the Earth and can make the moon appear" doesn't work and "supermoon is the full or new moon that occurs when the moon is at or near its closest approach to the Earth and appears" does.

The end of this sentence needs to logically convey whether computer technology can power economic growth in the same way that the steam engine and the printing press used to power economic growth when they were important. "whether computer technology can power economic growth like the steam engine and the printing press", "whether technology can power economic growth as the steam engine and the printing press do", and "if computer technology can power economic growth as the steam engine and the internal combustion engine of the past do" all compare computer technology to the PRESENT impact of the steam engine and the printing press on economic growth – clearly illogical as those have no impact today on economic growth today. "whether computer technology can power economic growth the way the steam engine and the printing press did" and "if computer technology can power economic growth like the way the steam engine and the printing press did" make the proper comparison between computer technology today and the steam engine and printing press in the past. "if computer technology can power economic growth like the way the steam engine and the printing press did" is wrong, however, because of the redundant and incorrect structure “like the way” and the incorrect conditional “if” that starts the clause. "whether computer technology can power economic growth the way the steam engine and the printing press did" uses the correct “whether” and makes a logical and proper comparison.

This problem features several subtle meaning-related errors, errors that are much easier to spot and understand if you use good Decision Points strategy to identify the major differences between answer choices.

Note first that choices "the approval ratings among his constituents and the stock market dropping rapidly, the president announced a series of spending initiatives to try stimulating"/"the approval ratings among his constituents and the stock market dropping rapidly, the president announced a series of spending initiatives trying to stimulate" and "the stock market and the approval ratings among his constituents dropping rapidly, the president announced a series of spending initiatives to try and stimulate"/"the stock market and with the approval ratings among his constituents dropping rapidly, the president announced a series of spending initiatives that will try to stimulate"/"the stock market and the approval ratings among his constituents dropping rapidly, the president announced a series of spending initiatives to try to stimulate" flip the order of "the approval ratings" and "the stock market." Is that important? In "the approval ratings among his constituents and the stock market dropping rapidly, the president announced a series of spending initiatives to try stimulating" and "the approval ratings among his constituents and the stock market dropping rapidly, the president announced a series of spending initiatives trying to stimulate", "the approval ratings among" applies to both nouns that follow it ("his constituents and the stock market"), creating an illogical meaning: the stock market doesn't give approval ratings! By changing that order and putting the stock market first, "the stock market and the approval ratings among his constituents dropping rapidly, the president announced a series of spending initiatives to try and stimulate", "the stock market and with the approval ratings among his constituents dropping rapidly, the president announced a series of spending initiatives that will try to stimulate", and "the stock market and the approval ratings among his constituents dropping rapidly, the president announced a series of spending initiatives to try to stimulate" fix that error, keeping "the approval ratings among" separate and applicable only to "his constituents."

In choice "the approval ratings among his constituents and the stock market dropping rapidly, the president announced a series of spending initiatives trying to stimulate", the phrase " the president announced a series of spending initiatives trying to stimulate" assigns the verb "trying" to the spending initiatives. But that's not logical either - initiatives are inanimate and can't "try" to do anything; it's the president trying to stimulate the economy, not the initiatives. So "the approval ratings among his constituents and the stock market dropping rapidly, the president announced a series of spending initiatives trying to stimulate" is also incorrect for a meaning reason.

"the stock market and with the approval ratings among his constituents dropping rapidly, the president announced a series of spending initiatives that will try to stimulate" makes a very similar meaning error: by saying "spending initiatives that will try to stimulate" this choice makes it seem again like the initiatives will try, and that just cannot be true.

Between "the stock market and the approval ratings among his constituents dropping rapidly, the president announced a series of spending initiatives to try and stimulate" and "the stock market and the approval ratings among his constituents dropping rapidly, the president announced a series of spending initiatives to try to stimulate", there is a one-word difference: "the stock market and the approval ratings among his constituents dropping rapidly, the president announced a series of spending initiatives to try and stimulate" has "try and stimulate" while "the stock market and the approval ratings among his constituents dropping rapidly, the president announced a series of spending initiatives to try to stimulate" has "try to stimulate." While in common speech you may be accustomed to hearing the two used interchangeably, the "and" creates a totally different meaning - by linking two parallel verbs ("try" and "stimulate"), "and" creates the meaning that those two actions are independent. That's an incorrect meaning: "stimulate" is exactly what the president is trying to do. "Try to stimulate" conveys that meaning properly, making answer choice "the stock market and the approval ratings among his constituents dropping rapidly, the president announced a series of spending initiatives to try to stimulate" correct.

In analyzing the decision points between the five answer choices, you should first notice the difference between “in ascribing” in "in ascribing these ailments to a psychological disorder", "in ascribing a psychological disorder as the cause for these ailments", and "in ascribing a psychological disorder to these ailments" and "if these ailments are ascribed" in "if these ailments are ascribed as the cause for a psychological disorder" and "if these ailments are ascribed to a psychological disorder". Additionally, you should see that "if these ailments are ascribed as the cause for a psychological disorder" and "in ascribing a psychological disorder as the cause for these ailments" contain the words “as a cause” while the other choices do not. Probably the easiest of those decision points to assess is the addition of “as a cause”. The word "ascribe" already means "to credit or assign, as to a cause or source" so "if these ailments are ascribed as the cause for a psychological disorder" and "in ascribing a psychological disorder as the cause for these ailments" are redundant. For "in ascribing these ailments to a psychological disorder" and "in ascribing a psychological disorder to these ailments" the use of the modifying phrase “in ascribing” illogically modifies the patients, suggesting that the patients are the ones doing the ascribing. Clearly, it is the doctor who is doing the ascribing and the “if” clause, which does not then modify the patients, makes the meaning logical. Correct answer is "if these ailments are ascribed to a psychological disorder".

This problem (like many others) tests logical meaning. Note the use of the word "other" in choices "As some of the busiest airports and ports in Europe, the United Kingdom has far more invasive species of certain types than does any other European country." and "With some of the busiest airports and ports in Europe, the United Kingdom has far more invasive species of certain types than does any other European country.", and compare that to the usage in "With some of the busiest airports and ports in Europe, the United Kingdom has far more invasive species of certain types than does any European country."/"Because of some of the busiest airports and ports in Europe, the United Kingdom has far more invasive species of certain types than does any European country."/"Because it has some of the busiest airports and ports in Europe, the United Kingdom has far more invasive species of certain types than any European country does.". Can the UK have more invasive species than any European country, when it is a European country itself? Logically, no - it can have the most of any country in Europe, but not more than any country. The best it can do is "tie" itself. So this sentence requires the use of "other" to be logically correct.

Then notice the major difference between "As some of the busiest airports and ports in Europe, the United Kingdom has far more invasive species of certain types than does any other European country." and "With some of the busiest airports and ports in Europe, the United Kingdom has far more invasive species of certain types than does any other European country.". The UK has some of the busiest (air)ports, but it is not itself the busiest airports and ports. So "As some of the busiest airports and ports in Europe, the United Kingdom has far more invasive species of certain types than does any other European country." is illogical, meaning that "With some of the busiest airports and ports in Europe, the United Kingdom has far more invasive species of certain types than does any other European country." must be the correct answer.

This problem provides two very clear decision points for you to get started:

1. "they" vs. "it" as the first word of the sentence

2. "that of" vs. "those of" vs. (no possessive) in relation to "the Medieval period"

The key to both of these is recognizing the subject of the sentence which is "global temperatures." Since temperatures is plural, the pronoun that corresponds to them must be "they" and you can eliminate choices "it has only recently eclipsed the Medieval period, during which, scientists theorize, a" and "it has only recently eclipsed that of the Medieval period, during which scientists theorize a".

Then notice that the comparison is between current global temperatures and the temperatures during the Medieval period; you cannot logically compare "temperatures" with the timeframe, so you need to have "those of" (which "they have only recently eclipsed those of the Medieval period, during which scientists theorize that a" and "it has only recently eclipsed that of the Medieval period, during which scientists theorize a" have but "they have only recently eclipsed the Medieval period, during which scientists theorize that a" does not) to properly draw the comparison.

Between "they have only recently eclipsed those of the Medieval period, during which scientists theorize that a" and "they have only recently eclipsed those of the Medieval period, during which, scientists theorize, a", notice that the only difference is commas around "during which." Why is that important? Here you're dealing with a tense/timeline decision. Since "theorize" is present-tense but the Medieval period is clearly in the past (even if you're not a historian, the fixed past tense "sent" outside the underline tells you that those volcanoes were in the past), you cannot have "scientists theorize" as part of the phrase "during which." The scientists currently theorize that volcanoes caused the global warming, so you need to separate that subject-verb from the modifier "during (the Medieval period)." This means that answer choice "they have only recently eclipsed those of the Medieval period, during which, scientists theorize, a" is correct.

In this sentence correction problem, it is very easy to access the decision points because there is only one word underlined! So the difference between those five choices to start the sentence obviously matters and you need to figure out why.

To do this you must look at the entire sentence - a classic example of the “Whole Sentence Matters” device used by testmakers. The primary issue is which of these modifiers creates logical meaning with the rest of the sentence. Clearly, the phrase must modify “rainforests”- and do rainforests “have” or “possess” a portion of the earth’s surface? Or do they just represent it? They simply are that portion of the earth’s surface, so only “as” "being" and “although accounting for” could be correct choices. Answer choices "With" and "Despite having" illogically suggest that rainforests have or are with 7% of the world's surface areas.

For the choice between "As", "Being" and "Although accounting for", the decision comes down to the meaning of the sentence. The rest of the sentence goes on to talk about what a large impact the rainforest have on the planet, but the introductory phrase talks about how rainforests are (only) 7% of the earth’s surface. Answer choices "As" and "Being" illogically suggest that the reason they have such a large impact is because they are such a small percentage of the earth's surface area! With that in mind, you see that the sentence requires a transition to set up a logical meaning – although rainforests represent a small area, they have a huge impact. Therefore, the phrase “although accounting for” is necessary, and the correct answer is "Although accounting for".