只有把太阳放置在太阳系的中心位置，其它行星的运动才解释得通。

Only if you put the sun at the centre of the solar system did the movements of the other planets in the sky __________ _________.

Some children are mad over video games. They just can't tear themselves away from them _______ they start.

A．since　　　　　　B．once　　　　　　 C．even if　　　　　D．as

He insisted that he _______ nothing wrong and that he _______ now.

A. did, be freed　　　　　　　　 B. had done, would be freed　

C. should do, should be freed　　　 D. should do, was

Historically, _______ main material for making tables has been wood, but ______ metal and stone have also been used.?

A. the; /　　 B. /; /?C. the; the 　 D. /; the

________ books you read, _______ knowledge you will gain.（ ）

A. The many; the more　　　　　　 B. The more; the much

C. The more; the more　　　　　　 D. The many; the much

He is good at (描述)________ what has happened to him.

It’s important for us to accept some new ______(概念) from foreigners.

The limited supply of water has been put into practice, take care to turn off the running ____ before you leave.

A. radio　 B. traffic lights C. gas　 D. tap

He spends as much time as he can______books.

A. reading　 B. read　　　　 C. reads　　　 D. to read