单项选择题

The serious environmental problem exist nowadays, because adequate measures for preventing them ______ taken in the past.

A. was not
B. were not
C. were not being
D. being not

<上一题目录下一题>

热门试题

单项选择题

I could not persuade him to accept it, ______ make him see the importance of it.

A. if only I could not
B. no more than I could
C. or I could not
D. nor could I

单项选择题

John could be a very excellent student but he ______ hard.

A. didn't work
B. wasn't working
C. doesn't work
D. hadn't worked

相关试题