A lot of tests ________ on a large number of rats in the past two years.

A．have been carried out

B．were carried out

C．have been carried on

D．were carried on

—Would you like to have a walk with us?

－________

A．A moment, I’d like to

B．For a moment, but I’d like to.

C．A moment and I’d like to go

D．A moment and I’d like to go to

When ________ why he had broken the law, the young man just looked at the policeman and said nothing.

A．being questioned

B．questioning

C．questioned

D．to be questioned

It is thought ________ 60 million people on the Net, connected up to over 15 million computers.

A．to be

B．there could be

C．to have

D．there to be

You’ll never learn to ride a bicycle if you don’t ________.

A．practice

B．drill

C．train

D．exercise

Watching children, particularly ________ they don’t know you are doing so, is really a pleasure.

A．as

B．when

C．while

D．since

The race was so close that everyone was ________his breath at the finish.

A．taking

B．holding

C．making

D．sending

________his food________ , the man had to come out of his hiding place.

A．Since; runs out

B．Because; has run out

C．With; running out

D．For; running out

——I’m sorry to ________ you to so much trouble.

——That’ s all right.

A．put

B．add

C．give

D．take

In my opinion, much attention should be paid________ education in the future.

A．to develop

B．in developing

C．developing

D．to developing