问题
选择题
It was not until the beginning of the twentieth century________to explore space.
A．did man begin
B．when man began
C．that man began
D．then man began
答案
答案：C
考查not until的强调句型。结构为：it is + not until+其它+that … ,故选C，句意为：就是直到二十世纪开始的时候人类开始探索太空。