The correct answer is "precipitation," which means water that falls from the sky in a liquid or solid form. "Precipitation" is the only answer choice that can ruin a picnic but is also needed to help plants grow. "Wind" and "ants" can ruin a picnic, but they do not directly help plants grow. "Sunlight" helps plants grow, but it is not something that will ruin a picnic.

The prefix "cent-" means one hundred, so a period of one hundred consecutive years is a “century.” To provide additional help, a “decade” is a period of ten consecutive years; a “millenium” a period of one thousand consecutive years, and a "dozen" twelve units of something taken as a group.

In this sentence, we know that Lisa acts immaturely. This means that she acts younger than her age at time. Since she is thirteen years old, the blank should be filled with a word that means someone who is younger than thirteen. An "infant" is a very young child, much younger than thirteen. Therefore, "infant" is the correct answer.

Here, the sentence provides enough context for the reader to realize that the dog is searching for his bone and was not successful in finding it. Therefore, it is the dog's "search" that is "fruitless" (ineffective). It would not make sense for his "hope," "desire," "appetite," or "bowl" to be fruitless.

Someone who is responsible for looking after someone else is called a “guardian.” A “champion” is someone who wins or has won something; a “competitor” is someone who takes part in a competition or someone who takes part in a game; an “actor” is someone who plays a role, like a movie star; and a “professor” is a teacher of college or university students.

Something that people have been doing for a long time is called a “tradition.” The word “supposition” is something you believe in but that there is no proof of; a “legend” is something from history that probably is not true but that people admire or like to talk about; a “conflict” is a fight; and “removal” means the act of taking something away.

The name given to arms and legs is "limbs." So, an arm is a “limb” and a leg is also a “limb.” To provide further help, a “notion” is an idea; “expressions” are sayings; a “hovel” is a shack or a small and messy house; and a “habitat” is an environment where something is meant to live, so a dolphin’s “habitat” is the ocean.

The condition of being very tired and exhausted is called “fatigue."

The context suggests that the correct answer is a place where “supporters,” or fans, go to watch a game. This means that the correct answer is “arena.” An “arena” is usually where a sports team plays. A “champion” is someone who has won a competition; a “triumph” is a great win; a “commentator” is someone who talks about what is going on during a sports game; and a “narrator” is someone in a story who is telling that story.

Because one of the students was rude to the other one, it makes sense that what began between them was some sort of fight or argument. This means the correct answer is “feud.” A “feud” is a long period of disagreement or dislike between two or more people. An “agreement” is a contract or shared plan. “Companionship” is the state of being around someone or friendship.