6．　 一生中

5．　 在中午

4．　 顺便问一下

3．　 在马路中间

2．　 遍布全国各地

1．　 在早上

20. He likes playing ______ football. His sister likes playing ______ piano.

19. ______ Huanghe River lies in ______ north of China.

18. After ______ breakfast he went to ______ school on ______ foot.

17. In China ______ first English textbooks were published in _____late nineteenth century.