单项选择题

Scientists say it may be five or ten years ______ it is possible to test this medicine on human patients.

A．since
B．before
C．after
D．when
<上一题 目录 下一题>
热门 试题

单项选择题
It is no ______ arguing about it, because he will never change his mind.
A．use
B．help
C．time
D．lively
单项选择题
When there are small children around, it is necessary to put bottles of pills out of ______.
A．reach
B．hand
C．hold
D．place
相关试题