单项选择题

Solar cells have been developed primarily ______ electric power for spacecraft.

A. to provide
B. providing
C. to offer
D. to give
<上一题 目录 下一题>
热门 试题

单项选择题
I think it my duty ______ your shortcomings.
A. to point out
B. to mention
C. to pick out
D. to remind of
单项选择题
The policeman entered the dark room,______
A. gun was in hand B. had gun in hand
C. gun be hand
D. gun in hand
相关试题