21.　　 It is lucky _______ you to go to London.

20.　　 That has nothing to do _______ me.

19.　　 I sometimes help my mother ______ the housework.

18.　　 What do you learn English _______?

17.　　 Thank you _______ helping me.

16.　　 The started the meeting ______ a song.

15.　　 Jim paid 1000 yuan _______ the bike.

14.　　 Jim spent 1000 yuan ______ the bike.

13.　　 I spent twenty years _____ writing the novel.

12.　　 They are good ________ boating.