—Why does the lake smell terrible?

—Because large quantities of water ______ .

　 A. have polluted　 B. is being polluted　 C. has been polluted　 D. have been polluted

______ , he never seems able to do the work beautifully.

　 A. Try as he does　 B. As he tries　　 C. Try as does he　　 D. As try he does

 The advantage human beings have to ______ the sun is worth discussing.

   A. take of          B. play with       C. take on            D. do with

 Peter has many friends, but ______ can help him.

   A. few of whom     B. few of that      C. few of which       D. few of them

 Mr. Smith, ______ of the ______ speech, started to read a novel.

   A. tired; boring    B. tiring; bored     C. tired; bored      D. tiring; boring

—______ you disturb her with these annoying questions just when she was busy cooking dinner?

— Sorry, I ______ that at that time.

　 A. Should; must not have done　　　　 B. Shall; may have done

　 C. Must; should do　　　　　　　　　 D. Must; should not have done

 If _____, please give him a hand, ______ you?

   A. asking; do     B. asked; will     C. being asked; don’t     D. to be asked; won’t

 We shall ______ our homeland, whatever happens.

   A. protect          B. guard           C. defend          D. prevent

 Mr. Ducan raised a question ______ he then failed to find an answer.

   A. to which        B. for which        C. with which       D. by which

 ______ that it took me an hour to figure out its reality.

A. What a complicated problem it was    B. So complicated the problem was

C. How complicated the problem was     D. So complicated was the problem