题目

----- In recent years,___ problem of global warning has been very serious.        ------That’s right. People are facing ____ number of natural disasters now.           A. 不填;   B. a; the   C. the; a  D. a; a 答案：C 解析: 考查冠词。全球变暖的问题是特指，a number of，许多，为固定表达。

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