问题

He failed the mid-term examination and only then _______ how much time he had wasted.

A:had he realized
B:did he realize
C:he had realized
D:he realized

正确答案是：

同类题型

下列各句中，加线的词语运用错误的一项是(　　)

The computer was used in teaching. As a result, not only _____, but students became more interested in the lessons.

There are millions of websites on the Internet and there ________ a lot of useful _________ on the websites.

After dinner, he used to football, but now he gets used to .

It’s fun tothe hills from the balcony.