第20题: [单项选择]The atmosphere ______ certain gases mixed together in definite proportion. A. consists of B. consists in C. insists on D. persists in 参考答案:A 答案解析:[分析] 本题考查动词短语辨析。选择中,consist of=be made up of或be composed of由…组成;consist in=lie in在于;insist on=persis