题目内容
Every possible means ________ to prevent the air pollution, but the sky is still not very clear.
[ ]
A.were using
B.have used
C.has been used
D.was used
答案:C
解析:
解析:
|
本题考查主谓一致及动词时态语态。means意思是“方式”,被every修饰,谓语动词用单数,排除A、B两项;but后的分词用了一般现在时,故此处用现在完成时的被动语态。 |
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