68. We can conclude from the passage that______.

　　 A. while pushing asteroids off course, nuclear weapons would destroy the world

　　 B. asteroids racing across the night sky are likely to hit Earth in the near future

　　 C. the worry about asteroids can be left to future generations since it's unlikely to happen now

　　 D. workable solutions still have to be found to prevent such a collision of asteroids with Earth

D

　　 Why do people pay a screaming soldier to order them to crawl under camouflage(伪装)netting before dropping to the ground to do 15 pushups?

　　 It's like the basic training that every new soldier hates. These people love it so much that they pay for it. And that's the way it is: three mornings a week at Venice Beach when these exercise fans go through。military-style obstacle course with difficulty. These are middle-class citizens looking for the most painful drills, not army men fighting for the higher ranks. They arrive in expensive sports cars, not troop carriers. They are not preparing for battle but building up health.

　　 It's a routine run by a tough soldier wearing a serious look. He and three other uniformed drill instructors shout orders. Two dozen men and women absolutely follow them. They struggle through sit-ups and a three-mile run down the beach before starting the obstacle course.

　　 Participants pay US $75 a week to do; what millions of soldiers have experienced for nothing，but a down-and-dirty training that is far from fit-keeping exercises in fitness club.

　　 Members do regular health club exercises, such as kick boxing, strength training and stretching. But the long-distance beach run and the obstacle course work up their sweat. That sets this routine different from traditional fitness exercises. Along with the wall-climbing and low-crawling, the course requires jumping over obstacles, rope climbing and pull-ups. Sweat pours down the face of the trainees and sand gets stuck to their hair as they climb over the obstacle wall. But all of them are happy when the daily training is over. They pay to sweat.

67. What do people think of the suggestion of using nuclear weapons to change the course of asteroids?

　　 A. It sounds practical but it may not solve the problem.

　　 B. It may create more problems than it might solve.

　　 C. It is a waste of money because a collision of asteroids with Earth is very unlikely.

　　 D. Further research should be done before it is proved useful.

66. What do scientists mainly talk about the collision of an asteroid with Earth?

　　 A. It is very unlikely but the danger of its happening exists.

　　 B. Such a collision might occur once every 50 thousand years.

　　 C. Collisions of smaller asteroids with Earth occur more often than expected.

　　 D. It's still too early to say certainly whether such a collision might occur.

65. What does the passage say about asteroids and meteoroids?

　　 A. They are heavenly bodies different in composition.

　　 B. They are heavenly bodies similar in nature.

　　 C. There are more asteroids than meteoroids.

　　 D. Asteroids are more mysterious than meteoroids.

64. We can know from the passage that

　　 A. the reason why ageing takes a greater loss on the male heart has been found out

　　 B. scientists are on the way to finding out why the male heart loses more of the cells

　　 C. the team has done something to prevent the male from suffering the greater loss

　　 D. women over 70 could lose more heart cells than those at the age of 20

C

　　 Unless we spend money to spot and prevent asteroids(小行星)now, one might crash into Earth and destroy life as we know it, say some scientists.

　　 Asteroids are bigger versions of the meteoroids(流星)that race across the night sky. Most orbit the sun far from Earth and don't threaten us. But there are also thousands of asteroids whose orbits put them on a collision course with Earth.

　　 Buy $50 million worth of new telescopes right now. Then spend $10 million a year for the next 25 years to locate most the space rocks. By the time we spot a destructive one, the scientists say, we'll have a way to change its course.

　　 Some scientists favour pushing asteroids off course with nuclear weapons. But the cost wouldn't be cheap.

　　 Is it worth it? Two things experts consider when judging any risk are: (1) How likely the event is; and (2) How bad the results if the event occurs. Experts think an asteroid big enough to destroy lots of life might strike Earth once every 500，000 years. Sounds pretty rare--but if one did fall, it would be the end of the world. "If we don't take care of these asteroids, they'll take care of us.”Says one scientist, "It's that simple.”

　　 The cure, though, might be worse than the disease. Do we really want fleets of nuclear weapons sitting around on Earth?”The world has less to fear from the terrible rocks than from a great nuclear fleet set against it,” said a New York Times article.

63. If you want to live longer, you should

　　 A. enable your heart to beat much faster　　　

B. find out the reason for ageing

　　 C. exercise regularly to keep your heart healthy　

D. prevent your cells from being lost

62. According to the text, the UK scientists have known that

　　 A. women have more cells than men when they are born

　　 B. women can replace the cells that enable the heart to beat

　　 C. the female heart loses few of the cells with age

　　 D. women never lose their pumping power with age

61. The text mainly talks about ______.

　　 A. men's heart cells　　　　　　　　　 B. women's ageing process、

　　 C. the gender difference　　　　　　　 D. hearts and long life

60. The underlined word“longevity" in the second paragraph probably refers to ______.

　　 A. health　　　　　 B. long life　　　　 C. ageing　　　　　 D. effect

59. When reporting the news, the author seemed to be a little ______.

　　 A. angry　　　　　 B. surprised　　　　 C. shocked　　　　 D. worried

B

　　 Why do men die earlier than women? The latest research makes it known that the reason could be that men's hearts go into rapid decline when they reach middle age.

　　 The largest study of the effects of ageing on the heart has found that women's longevity may be linked to the fact that their hearts do not lose their pumping power with age.

　　 "We have found that the power of the male heart falls by 20--25 percent between 18 and 70 years of age,”said the head of the study, David Goldspink of Liverpool John Moores University in the UK.

　　 "Within the heart there are millions of cells that enable it to beat. Between the age of 20 and 70，one-third of those cells die and are not replaced in men,”said Goldspink. "This is part of the ageing process."

　　 What surprises scientists is that the female heart sees very little loss of these cells. A

healthy 70-year-old woman's heart could perform almost as well as a 20-year-old one's.

　 "This gender difference might just explain why women live longer than men,”said Goldspink.

　　 They studied more than 250 healthy men and women between the ages of 18 and 80，focusing on healthy persons to remove the confusing influence of disease.

　　 The team has yet to find why ageing takes a greater loss on the male heart, said Goldspink.

　　 The good news is that men can improve the health of their heart with regular exercise. Goldspink stressed that women also need regular exercise to prevent their leg muscles becoming smaller and weaker as they age.