Directions: For each blank in the following passages there are four words or phrases marked A,B, C and D. Fill in each blank with the word or phrase that best fits the context.

　　　　　　　　　　　　　 (A)

It is very important to have healthy teeth. Good teeth help us to chew our food. They also help us to look nice.

How does a tooth go bad ? The (51 ) begins in a little crack in the enamel ( 珐琅) covering of the tooth. This happens after germs and bits of food have (52) there. Then the decay slowly spreads inside the tooth. In the end, poison goes into the blood ,and we may feel ill.

How can we keep our teeth (53) ? First, we ought to visit our dentist twice a year. He can fill the small holes in our teeth before they destroy the teeth. He can (54) our teeth to check that they are growing in the right way. (55) , may people wait until they have toothache before they see a dentist. Secondly, we should brush our teeth with a toothbrush and fluoride( 氟化物) toothpaste at least(56) a day ----- one after breakfast and once before we go to bed. We can also use wooden toothpicks to(57) between out teeth after a meal. Thirdly, we should eat food that is (58) to our teeth and our body: milk, cheese, fish, brown bread, potatoes, red rice, raw vegetables and fresh fruit. Chocolate, sweets, biscuits, and cakes are bad, especially (59) we eat them between meals. They are harmful because they (60) our teeth and cause decay.

51. A. destruction　 B. decay　　　 C .fault　　　 D .hurt　

52. A. stored　　　 B. collected　 C .laid　　　 D .piled　

53. A. healthy　　 B. complete　 C. effective　 D. painless

54. A. observe　　 B. skim　　　　 C. watch　　 D. examine　

55. A. Unexpectedly B. Certainly small　 C. Unfortunately　 D. Generally

56. A .once　　　 B. twice　　　 C. three times D. four times　

57. A .drill　　　　 B. dig　　　　 C. clean　　　 D .explore　

58. A. delicious　　 B. valuable　　 C. beneficial　 D. meaningful

59. A .what　　　 B. how　　　　 C. whether　　 D .when 　

60. A .stick to　　 B. attach to　　 C. fix on　　 D .keep to　

50. If you ______ any problems when you arrive at the airport, give me a ring.

A.　　　 come up with　 B. set about　 C. run into　 D. put aside　

49. It is good for elderly people to be ______ involved in community service.

A. honestly　 B. patiently　 C. eagerly　 D. actively

48. Although he ahs taken a lot of medicine, his health _____ poor.

　 A. proves　 B. remains　 C. maintains　 D. continues　

47. After much ______, the shop owner agreed to cut down the price by 20%.

　 A. debating　 B. talking　 C. discussing　　 D. bargaining　

46. It can’t a(n) ____ that four jewelry stores were robbed in one night.

　cidence　 B. accident　 C .incident　 D. chance　

45. I saw Bob play the piano at John’s party and on that _____ he was simply brilliant.

　 A. scene　 B. circumstance　 C. occasion　 D. situation　

44. Please follow you supervisor’s instructions, or you’ll _______ him.

　 A. discourage　 B. offend　 C. disturb　 D. bother　

43. For the sake of her daughter’s health, she decided to move to a warm ______________.

　 A. weather　　 B. temperature　 C. season　 D. climate　

42. It seems difficult to ______ “hurt” from “injure” in meaning.　

　 A .judge　 B. tell　 C .divide　 D .separate