21. 11.My brother is very good at 　　　　(唱)English songs.

20. It is hard to 　　　　(选择)between staying with my parents and going abroad.

19. When doing shopping, Sam is always slow to make a 　　　　(决定).

18. The shopping-mall is on 　　　　(营业)from 9:00 a.m. to 10:00 p.m.

17. I don’t have much money, but my life is 　　　　(有意义的)

16. I live on the 　　　　　floor of this building.

B)根据句意和所给汉语，写出相应的单词。

15. We should try our best to help people 　　　　.

14. At a very young age, he is 　　　　　in keeping pets.

13. Outdoor activities are good for us to keep 　　　　.

12. People kill animals because they want to 　　　　　from their bones.