The sentence needs to remain parallel. If it had said "cooking," "mountain-climbing" would be ok.

This is a faulty comparison. "Sandwiches" cannot be compared to a cafeteria. Use "similar to those at the cafeteria" or something like that instead to correct the sentence's error.

When making comparisons you must be careful to compare like things. In this case, the sentence as written makes a comparison between "cookies" and "my grandmother." You want to compare cookies to cookies. You can fix this error by making "grandmother" into a possessive, singular noun, "grandmother's." This way, it is inferred that the subject being spoken about is the speaker's grandmother's cookies, not the speaker's grandmother herself.

This sentence contains parallelism—in this case, a set of sequential actions set off by commas. In sentences that have a parallel structure, all similar parts of speech should follow the same format. So, the list should read, "sifting the flour," "separating the eggs," and "putting it in the oven to bake." Instead, the way the sentence is currently written, "we put" inserts a needless repetition of the subject that interrupts the logical flow of the sentence by putting the verb in a different tense.

The correct answer is "than other artists."  As the sentence reads, it is saying that Anna thinks her friend's art is more creative than other artists, which is an incorrect comparison; she should be comparing her friend's art to the art of other artists, not to the artists themselves.

A correct phrasing would be "At the student art showcase, Anna enjoyed seeing her friend Zoe's abstract paintings, which she thought were more creative than the works of the other artists."

The verb phrase "will attend" should be changed to "attending" because it is part of a list of "-ing" verbs, all of which need to be in the same form in order for the sentence to use proper parallel structure. Since "running," "shopping," and "cooking" are already conjugated in the same way, "will attend" should be conjugated in this way too, and therefore should be changed to "attending."

This sentence lacks parallel structure between the elements in the list. Items in a list should be formatted in the same way grammatically. The corrected sentence reads, "The woman slowly became fascinated by the aliens’ strange culture, their intelligence, and their hilarious jokes."

Only like things can be compared. "My apartment" can be compared to "that of my boss" or my "boss'."

It is important for a sentence to use correct parallelism, which means that listed items should take on the same grammatical form. Here, the first two listed items are nouns ("amazing food" and "high quality wine"). Therefore, the third item should also be a noun; however, “attracts” is a verb, and therefore is incorrect. To fix the sentence, one might omit the word "attracts," leaving simply "amazing food, high quality wine, and a wealthy clientele," three nouns.

This sentence has a problem with parallelism. Since the first part contains a verb, the second part must as well. The corrected sentence reads: I had expected to learn many essential survival skills at the workshop, but instead I only learned how to open a can without a can opener.