Rewrite the sentences.

31. The reason for which the president will come to that city hasn't been told yet.

32. We enjoyed the city in which we spent our vacation.

33. He is curious about the reason for which she has been sad in recent days.

34. We enjoy traveling to Dalat where there are a lot of places of interests.

35. The bed on which I sleep has no mattress.

36. There wasn't any directory in the telephone box from which I was phoning.

37. The girl to whom I introduced you is John's sister.

38. The shop from which I bought the shoes is closed.

39. My English teacher is Mr. Tam, for whom I had a great respect.

40. Lan's party to which we are all invited is next Sunday evening.

41. The film "The Lost World", about which I've heard good reports, is showing next week.

42. The people like her very much who works with them.

43. Mr. and Mrs. Wang, with whom we went on holiday, live in Shanghai.

44. She was left the money by her former husband from whom she divorced in 1996.

45. The bus for which we had been waiting didn't come.

46. It is her unmarried name by which she is better known.

47. This is the story of a man whose wife suddenly loses her memory.

48. A man brought in a small girl whose husband had been cut by flying glass.

49. They volunteer to help the victims whose houses were destroyed by a flood.

50. The birds whose nests I found in the tree behind my house have flown away.

51. The shop assistant to whom I spoke was very nice and helpful.

52. The shop to which they went was on Le Loi street.

53. A man who answered the phoned told me you were away.

54. A waitress who served us was very impolite and impatient.

55. A girl who was injured in the accident is now in hospital.

56. A building that was destroyed in the fire has now been rebuilt.

57. Many rivers and lakes around the world are polluted which caused serious diseases to people using the river water.

58. We'll have to get across the frontier which will be difficult.