【题目1】Once environmental damage ___________, it takes many years for the system to recover.
A. has done B. is to do
C. does D. is done
【题目2】Edison made a lot of inventions, ___________of great importance.
A. which I think are B. which I think they are
C. I think they are D. that I think are
【题目3】________ you picked up the watch?
A. Where it was that B. Where was it that
C. Where was it there D. It was where that
【题目4】Only ________did the match start.
A. when the rain stopped B. the rain stopped
C. the rain had stopped D. did the rain stop
【题目5】__________ has already been pointed out, grammar is not a set of dead rules.
A. It B. Which
C. As D. What