Once environmental damage_____ it takes hundreds of years for the system to recover.A.has
专四
已帮助 人
Once environmental damage_____, it takes hundreds of years for the system to recover.
A.has done
B.is to do
C.does
D.is done
请帮忙给出正确答案和分析,谢谢!
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正确答案:D
本题综合考查动词的时态和语态。句中主句的谓语动词takes用的是一般现在时,根据条件从句中时态的替代,从句中也应该用一般现在时表将来时,由于主语是envi—ronmentaldamage,所以谓语动词要用被动语态。
