31. I knocked on his door but nobody came to answer it.
32. Do you think you can do it by yourself?
33. The People's Republic of China （PRC）, founded on October l , 1949, covers an area of 9. 6 million square kilometers.
34. People all over the world are trying to help the people in the quake-stricken areas.
35. We must take some measures to control the pollution.
36. The Olympic Games is an international sports event that takes place every four years.
37. He was very happy to hear from his old friend.
38. He has a foreign friend who lives in the United States.
39. A friend of mine from high school is working in England now.
40. She likes to help any one who is in difficulty.
41. Trees need water to grow.
42. The doctor told me to have more water.
43. Who can help me clean the room?
44. We should encourage him to have confidence in himself.
45. The traffic jams during morning and afternoon rush hours are a headache in big cities now.
46. Apples here like water and sunshine.
47. Fred was such a hardworking student that he soon came out first in the class.
48. Ted and William have lived under the same roof for five years.
49. A lot of natural resources in the mountain area will be exploited and used.
50. Do you have access to the Internet?
51. The students are encouraged to do more listening, reading and writing by their teacher.
52. There is a large amount of energy wasted due to friction （摩擦）.
53. This place has plentiful material resources.
54. Various substances differ widely in their magnetic （磁性的） characteristics.
55. The more passions we have, the more happiness we are likely to experience.
56. Each time history repeats itself, the price goes up.
57. In an age of plenty, we feel spiritually hungry.
58. In no other country in the world can you find such plants as this one.
59. I was having a nap when suddenly the telephone rang.
60. All that glitters is not gold.