Now that she is out of a job, Lucy ________ going back to school, but she hasn’t decided yet．

A．had considered

B．has been considering

C．considered

D．is going to consider

The two friends ________ on the Internet for three hours, and they would go on till the next morning．

A．had been chatting

B．had chatted

C．were chatting

D．have been chatting

－Hi, Tracy, you look tired．

－I am tired．I ________ the living room all day．

A．painted

B．had painted

C．have been painting

D．have painted

China sent up Shenzhou V manned spaceship into space successfully, which shows science and technology ________ rapidly in China．

A．have been developing

B．develops

C．is developing

D．had developed

Whatever is worth ________ at all is worth ________ well．

A．doing; doing

B．being done; doing

C．to do; being done

D．being done; being done

You should understand the traffic rule by now．You’ve had it ________ often enough．

A．explaining

B．to explain

C．explain

D．explained

Unless ________ to speak, you should remain silent at the conference．

A．invited

B．inviting

C．being invited

D．having invited

When ________, the museum will be open to the public next year．

A．completed

B．completing

C．being completed

D．to be completed

The researcher is so designed that once ________ nothing can be done to change it．

A．begins

B．having begun

C．beginning

D．begun

________ such heavy pollution already, it may now be too late to clean up the river．

A．Having suffered

B．Suffering

C．To suffer

D．Suffered