The acid rain is one of the chain reactions that ______ by environmental pollution
A.is come about
B.is caused
C.are given birth
D.are brought about
为什么选D不选B
人气：115 ℃ 时间：2020-05-10 14:45:16
解答
因为that 后面的内容是修饰 chain reactions,是复数,如果B是 are caused就可以选了.
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