问题描述:
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
A.is come about
B.is caused
C.are given birth
D.are brought about
为什么选D不选B
问题解答:
我来补答展开全文阅读