The boys were climbing ______ on the rocks.

[　　]

I hardly knew ______ write to you.

[　　]

A. how can

B. how can I

C. to

D. how to

Do you know which countries ______ the festivals _______ ?

[　　]

A. are, from

B.不填，come from

C.不填，are come

D. does, come form

Please practise _____ and _____ an opinion.

[　　]

A. expressing, to support

B. to express, to support

C. expressing, supporting

D. to express, supporting

Lizzy said she had a lot of interesting ________ during her stay in China.

[　　]

As a farmer, he has ________ agriculture.

[　　]

A. a knowledge about

B. good knowledge of

C. a good knowledge of

D. good knowledges of

--Have you considered ________ there?

--Yes, I am thinking of going there by plane.

[　　]

The scientist spent all his spare time ________ experiments ________ chemistry.

[　　]

--Did you find your watch yesterday?

--No, I didn't find ________, but I've bought ________.

[　　]

We'll correct our mistakes, no matter who points ________.

[　　]