_____ the day went on, the weather got worse.
| A．With | B．Since | C．While | D．As |
Scientists say it may be five years ______ it is possible to test this medicine on human patients．
| A．since | B．until | C．before | D．when |
Last month, the Japanese government expressed their thanks for the aid they ______ from China.
| A．receive | B．had received | C．have received | D．are receiving |
If you _____ smoke, please go outside because this is a non-smoking office.
| A．must | B．should | C．can | D．may |
––Who would you rather _____ your graduation ceremony tomorrow, your parents or friends?
––All of them.
| A．will have attended | B．have attended | C．attended | D．to attend |
In that school, English is compulsory for all students, but French and Russia are ____ .
| A．special | B．optional | C．regional | D．original |