问题

The central heating system of this office building isdown and several workers ______ it right now.

A:had repaired
B:haverepaired
C:repaired
D:are repairing

正确答案是：

同类题型

was younger, I’d often go for _____ drive withsome friends, purely for _____ enjoyment of it.

Which of the following sentences is wrong

kept his head _____ water when hebegan to learn swimming, but he raised his head now and then

Daniel is my friend. I like to share my with him when 1 am happy.

Would you like ______ a football match