Now scientists are _________ to solve the problem about river pollution.

[　　]

________ two tickets for the new play at the Grand Theatre on Saturday. Shall we go and see it together?

[　　]

A．They have been given

B．I have been given

C．I am given

D．They have given to me

The reason for all the changes being made ________ to us yet.

[　　]

A．has not explained

B．has not been explained

C．did not explained

D．were not explained

Tim ________ since he lost his job three weeks ago.

[　　]

A．had been unemployed

B．was unemployed

C．has been unemployed

D．has unemployed

My pictures ________ until next Friday.

[　　]

--What do you think made Mary so upset?

--________ her new bicycle.

[　　]

See the flags on top of the building? That was ______ we did this morning.

[　　]

We were swimming in the lake _______ suddenly the storm started.

[　　]

The girl ________ become one of the Supergirls, but failed.

[　　]

“If anyone ________, it’s me.” The girl said, murmuring.

[　　]