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

单项选择题
There is no mother ______ loves her children.
A．which
B．who
C．that
D．but
单项选择题
The ______ of the clock showed that it was time for lunch.
A．fingers
B．arms
C．hands
D．figures
相关试题