55. A ripe apple will fall to the earth by _____ .

A. itself’s force                     B. earth’s force

C. magnetic force                  D. man’s force

54.Which of the following is true according to the letter?
 A. Hua arrived in Beijing on Friday night   B. Hua arrived in Beijing on Sunday night
 C. Hua arrived in Beijing on Monday night  D. Hua arrived in Beijing on Saturday night

B

There are many problems connected with space travel. The first and greatest of them is gravity（地球引力）. If you let your pencil drop to the floor, you can see gravity in action. Everything is held down to the earth by magnetic（磁）force. The weight of something is another way of describing the amount of force taking place on it by gravity. A rocket must go at least 2,500 miles an hour to take anyone out of the gravity of the earth into space.

Once out of the earth’s gravity, an astronaut is affected by still another problem―weightlessness. Here, if a pencil drops, it does not fall. If a glass of water is turned upside down, the water will not fall out. All of us who are used to gravity expect things to have weightless conditions.

Recent long flights have shown that the body needs special exercise in a spaceship.

Hua                                                                                                              
51.Where did Hua write the letter? In _______ .
 A. Nanjing      B. Hangzhou       C. Beijing        D. Shanghai
52. How many days did Hua and her mother stay there to the time she wrote the letter? 
 A. Three days.   B. Five days.       C. Eight days.     D .Eleven days.
53.Where did Auntie take Hua to on Sunday afternoon?

 A. The Summer Palace.              B. The Great Wall.   

C. Beihai Park.                     D. Tian’anmen Square.

50. A. cheap         B. big                 C. high           D. large

49. A. yen          B. money             C. telephone      D. price

48. A. had          B. made               C. sold           D. put

47. A. interesting    B. bad                C. lucky          D. suitable

46. A. possible       B. impossible         C. easy          D. necessary

45. A. shops         B. Japanese          C. telephones     D. numbers