高中英语现在进行时的被动语态单选题

8.Customers are asked to make sure that they ____ the right change before leaving the shop.  

A．will give	B．have been given
C．have given	D．will be given

7.Although the causes of cancer ____， we do not yet have any practical way to prevent it.  

A．are being uncovered	B．have been uncovering
C．are uncovering	D．have uncovered

6.I have to go to work by taxi because my car ____at the garage.

A．will be repaired	B．is repaired
C．is being repaired	D．has been repaired

5.---Have you handed in your schoolwork yet?
　---Yes，I have. I guess it ____ now.

A．has graded

B．is graded

C．is being graded

D．is grading

一Ready to give up guessing，Sandy?
一No，no，hold on! I think I______ at the answer now．

A．arrive

B．am arriving

C．have arrived

D．will arrive

--- Would you care for a cup of coffee?
--- I ________ one. Thank you just the same.

A．had

B．have had

C．would have

D．will have