Sheep, like any warm-blooded animal in the world, ________ an active life in winter．

A．lives

B．lived

C．is living

D．live

What’s really needed, according to most researchers in this field, ________ a“killer”application(应用)particularly suited for the way DNA computing solves problems．

A．being

B．are

C．is

D．was

If you go to Beijing, you’ll find the Summer Palace more magnificent(壮丽的)than commonly ________．

A．supposing

B．supposed

C．to suppose

D．suppose

My mother ought to stop work; she has a headache because she ________ too long．

A．read

B．has been reading

C．is reading

D．had read

It’s up to you to decide whether to ________ physics or chemistry．

A．take off

B．take on

C．take in

D．take up

All books ________ too much space will be returned this afternoon．

A．to taken

B．taking on

C．taking up

D．to take off

－Why are you so late?I ________ here for more than an hour．

－I’m terribly sorry．I overslept and missed the bus．

A．am waiting

B．was waiting

C．have been waiting

D．have been waited

－Can I help you, sir?

－Yes, I bought this radio here yesterday, but it ________．

A．didn’t work

B．won’t work

C．can’t work

D．doesn’t work

Our teacher told us that the earth ________ from west to east．

A．turns

B．turn

C．has turned

D．will turn

I won’t go to her birthday party unless I ________ invited．

A．was

B．will be

C．am

D．am being