单项选择题

If computers ______, many problems on space flight could not have been solved.

A．had not been invented
B．are not invented
C．were not invented
D．have not invented
<上一题 目录 下一题>
热门 试题

单项选择题
In the sentence Coal is sometimes called stored-up sunlight , the italicized part is a(n)
A．object complement.
B．subjective complement.
C．object.
D．appositive.
单项选择题
Which of the following sentences is INCORRECT
A．This pair of trousers costs fifty dollars.
B．Either my grandsons or their father is coming.
C．The British police has only very limited powers.
D．A committee of twelve men is to discuss the matter.
相关试题