—May I open the window to let in some fresh air?—________!
It is a good plan in theory, but it _____ to be seen whether it works in practice.
What do you think of the reason _____ he gave at the meeting yesterday?
Scientists say it may be five or six years ____ it is possible to test this medicine on human patients.
Every minute must be made full use of ____ our lessons, for the final examination is coming.
The foreigner does speak Chinese well, but of course not _____ we Chinese.