问题

We were told not to touch the equipment inthe laboratory unless ________.

A:although
B:allowing to do
C:allowed to
D:allowing to

正确答案是：

同类题型

Without electricity human life ________ quite different today.

I must apologise ________ you so late

In the last few years thousandsof films ____ all over the world

If it ____tomorrow, I’d go downtown with mybrother.

t drink now, but I ______ for almost ten years.