1.-How many workers are there in your factory?　　　 -There are two 　　　　.

A. hundreds　　　　 B. hundred　　　 C. hundred of　　 D. hundreds of

17. be used to doing sth.(习惯做某事)

16. prefer doing sth. to doing sth.

15. mind (my/…) doing sth.

14. spend some time (in) doing sth.

13. devote some time to doing sth.

12. keep sb. doing sth.

11. practice doing sth.

10. do some/ the + doing( shopping/ reading/ washing/ cooking/ cleaning/…)

9. go + doing( swimming/ skating/ walking/ hiking/ fishing/ shopping/jogging/…)