21.___safety, it is compulsory for all motorcyclists to wear helmets in our city.

  A. Ensuring   B.To ensure   C. Ensured   D. Having ensured

22.—I have found a perfect man for this job.

  —_____ !

 A. Good idea   B. Fantastic   C. What a pity   D. Good luck

23.It being Sunday£¬ I____ early. So I stayed in bed until 9 o’clock this morning.

A. couldn’t have got up    B. didn’t need to get up

C. shouldn’t have got up   D. needn’t have got up