56. 大多数水果来自树木。

Most of the fruits             trees.

54. It’s a fine day about        ( dig) holes by the lake to plant trees.

55. You can improve (提尚) your English by        (join) an English club.

52. Look!The boys are        (lie) on the beach and enjo- ying the sun.

53. The phone is        (ring) . Please answer it now.

50. Trees can provide better places for animals and birds        (live) in.

51. Trees are like        (fight) . They can keep air cool and clean.

48. We use trees to do a lot of useful things in our (life) .

49. He left without        ( say ) any words.

46. What a tall tree!It has long        ( branch) and thick leaves.

47. In big cities,air        ( pollute) is becoming worse than before.

44. We can’t i  a world without animals or trees.

45. Look!The girl is planting a tree in a h  .

42. Some forests are in danger. So people are trying to s  them.

43. To have a better living environment,we must fight a  pollution.

40. Let’s help save this small tree. It has got a        (疾病) .

41 .The p        trees are always green around the year.

38. The       (气体) from the paper factory smells very bad.

39. There are a lot of       (家具) in the house.