＿＿＿the people have become the master of their own country＿＿＿science can really serve the people.
| A．It is only then； that | B．It was that； when |
| C．It is only when； that | D．It was when； then |
Many accidents________ by careless drivers last year.
| A．are caused | B．were caused | C．have caused | D．will cause |
Studying in groups is necessary_____ you want to do well in school.
| A．if | B．until | C．unless | D．though |
You can hardly imagine the ______ they went ______.
| A．suffering; through | B．concern; through |
| C．recovery; over | D．worry; over |
---He didn’t go to the concert yesterday, did he?
---_______, he was studying for the tests all day.
| A．No, he didn’t | B．Yes, he did | C．No, he did | D．Yes, he didn’t |
I have been to Shanghai. I______ there last month.
| A．go | B．went | C．has gone | D．will go |