[单选题]When it _____ air pollution,Beijing faces the three “C” s,cars,coal and construction,which lead to Beijing's thick air pollution．(1分)
Arefers to
Bcomes to
Chappens to
Dspeaks to
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参考答案
试题答案：
B
答案解释：
解题思路： A.refers to 有“提及”的含义,可以提及人也可以是物.如He never referred to his sisters in his letters.他在信里从未提到过他的姊妹； comes to 有苏醒 和 总计的意思；happens to 发生；speaks to 后接 sb.,和.说话
