The idea that most people usually behave in a calm and reasonable way is (refuted, numbed) I think refuted
Each time she answered a guestion correctly, she rewarded herself with a (smug, ravenous) little smile of self-congratulation. I think ravenous
Florence's illness, after she had been chosen for the leading role in the class show, was a serious (setback, commentary) setback
Two are correct; one is incorrect.
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You are correct with your first answer. The idea that most people usually behave in a calm and reasonable way is refuted.
To determine the correct answer, one can examine the context and meaning of the sentence. The word "refuted" means to prove a statement or belief to be false or incorrect. In this case, the sentence implies that the idea that most people usually behave in a calm and reasonable way is contradicted or proven to be untrue.
For the second question, the correct answer is actually "smug." When someone is described as having a "smug" little smile, it means they are displaying a self-satisfied or superior attitude. The word "ravenous" means extremely hungry, which doesn't fit the context of the sentence.
To answer the third question, the correct answer is "setback." A setback refers to a reversal or hindrance in progress or development. In this case, Florence's illness acted as a significant obstacle or setback after she had been selected for the leading role in the class show. The word "commentary" refers to the act of expressing opinions or offering analysis, which doesn't fit the context of the sentence.