37. China has a large __________(人口).

36. Be ________(礼貌) to others!

35. The guard shouted at the naughty boy with his finger ________ (指) at him.

34.　 ___________(政治) is more difficult than physics.

33.　 ----Thank you for helping me with my English.　　

----My ________(乐事)

32.He found it hard to ________(取悦) his wife.

31.　 ________(塑料) Should not be used.

30.　 There is much difficulty in __________(种植) trees in the desert.

29.　 These model _________(飞机) can fly high in the sky.

28.Say it in _________(简明) English.