21. Students n                 to study hard.

22. I don't like young people who wears strange c                 with colorful hair.

23. Look at that girl. Her s                 is very nice.

24. Fifteen and fifteen is t                .

25. There are t                 months(月) in a year.

26. The p                 of the computer is 5,000 yuan. I can't afford(买得起) it.

27. All the clothes are on s                 for only 15 dollars each.

28. It's hot today, but he still wears a shirt and t                . I like a T-shirt and shorts better.

29. --- How much is the book?

--- Twenty d                .

30. A quarter (一刻钟) has f                 minutes(分钟).

31. Jane can play the piano, but she can't play it well. She n                 to practice more.

32. Our parents provide us with food and c                 and never ask for anything in return.

33. Put on your s                . It's a bit cold.

34. My class has t                 students, ten girls and twenty boys.

35. --- What's two and ten?

--- It's t                .

36. The p                 of the computer is 5000 yuan. I can't afford it.

37. This beautiful MP5 is on s                 in that shop, and it is very cheap, you can go and buy it.

38. This pair of t                 is too short for me.

39. --- How much are the trousers?

--- They're only ten d                .

40. Seven and eight is f                .

41. My brother is                 (十三) this year.

42. I want to buy                 (十一) watermelons.

43. Look at his new                 (裤子). T