－How long do you think it will be ________ China sends a manned spaceship to the moon?

－Perhaps two or three years．

A．when

B．until

C．that

D．before

The moment the 28th Olympic Games ________ open, the whole world cheered．

A．declared

B．have been declared

C．have declared

D．were declared

The construction of the two new railway lines ________ by now．

A．has completed

B．have completed

C．have been completed

D．has been completed

The weather turned out to be fine yesterday．I ________ the trouble to carry my umbrella with me．

A．should have taken

B．could have taken

C．needn’t have taken

D．mustn’t have taken

As the busiest woman in Norton, she made ________ her duty to look after all the other people’s affairs in that town．

A．this

B．that

C．one

D．it

－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

You won’t know if the coat fits you until you ________ it on．

A．will try

B．are trying

C．tried

D．have tried

They ________ friends since they met in Shanghai．

A．have made

B．have become

C．have been

D．have had

－The window is dirty．

－I know．It ________ for weeks．

A．hasn’t cleaned

B．didn’t clean

C．wasn’t cleaned

D．hasn’t been cleaned

The first use of atomic weapons was in 1945, and their power ________ increased enormously ever since．

A．is

B．was

C．has been

D．had been