I am sorry you’ve been waiting so long, but it will still be some time __________ Brain gets back．
| A．since | B．before | C．till | D．after |
It is a good plan in theory, but it _____ to be seen whether it works in practice.
| A．keeps | B．stays | C．stands | D．remains |
What do you think of the reason _____ he gave at the meeting yesterday?
| A．why | B．for which | C．that | D．in which |
Scientists say it may be five or six years ____ it is possible to test this medicine on human patients.
| A．since | B．after | C．before | D．when |
Every minute must be made full use of ____ our lessons, for the final examination is coming.
| A．going over | B．to go over | C．go over | D．to going over |
The foreigner does speak Chinese well, but of course not _____ we Chinese.
| A．as fluent as | B．more fluent than | C．so fluently as | D．much fluently than |