问题
选择题
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
答案
答案:D
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
答案:D