单项选择题

For years, doctors ______ millions of patients' lives with the help of ______ microscopes.

A．have saved
B．are saving
C．will save
D．were saving
<上一题 目录 下一题>
热门 试题

单项选择题
The conference ______ in Beijing next week is bound to be a great success.
A．holding
B．being held
C．to hold
D．to be held
单项选择题
Once more I have to leave Beijing, ______ I have been living for eight years.
A．that
B．where
C．which
D．as
相关试题