________ certain that his invention will lead to the development of production．

A．That's

B．This is

C．It's

D．What's

________ he is doing seems quite difficult．

A．How

B．That

C．Which

D．What

________ knows the truth about it will tell you．

A．Who that

B．That

C．Whoever

D．That who

________ I accept the gift or refuse it is none of your business．

A．If

B．Whether

C．Even if

D．No matter when

________ we need more practice is quite clear．

A．When

B．What

C．That

D．/

It surprised me a lot ________ he was shot to death there．

A．when

B．for

C．why

D．that

There is no doubt ________ he will come here to take part in the sports game．

A．whether

B．that

C．if

D．which

－I drove to Zhuhai for the air show last week．

－Is that ________ you had a few days off?

A．why

B．when

C．what

D．where

A computer can only do ________ you have instructed it to do．

A．how

B．after

C．what

D．when

It is necessary that a college student ________at least a foreign language．

A．masters

B．should master

C．mastered

D．will master