问题

Never before _____so highly successful in his attempts to change the weather slightly on a very small scale. [ ]

A: man has been
B: man is
C: will man be
D: has man been

正确答案是：

同类题型

The island country is _______ its clean waters and clear skies, which are free _____ pollution ofany kind. [ ]

It was ______ computer games that cost the boy a lot of time that he ought to have spent on his lessons.

in the repair shop, he drove his brother’sinstead

I ___ sitcoms, because they’re boring.

Now things made by machine are cheaper thanthose made _____.