3. The advantage of chevrons over straight，horizontal bars is that the former __________.

　 A) can keep drivers awake 　　B) can cut road accidents in half

　 C) will have a longer effect on drivers 　　D) will look more attractive

2. On roads painted with chevrons drivers tend to feel that __________.

　 A) they should avoid speed-related hazards 　　B) they are driving in the wrong lane

　 C) they should slow down their speed 　　D) they are approaching the speed limit

1. The passage mainly discusses _________.

　 A) a new way of highway speed control 　　B) a new pattern for painting highways

　 C) a new approach to training drivers 　　D) a new type of optical illusion

5. Which of the following best describes the author's tone in this passage?

　 A) Optimistic. 　　　　B) Critical. 　　　　C) Objective. 　　　　D) Arbitrary.

Passage 5

Believe it or not, optical illusion (错觉) can cut highway crashes.

Japan is a case in point. It has reduced automobile crashes on some roads by nearly 75 percent using a simple optical illusion. Bent stripes，called chevrons (人字形) painted on the roads make drivers think that they are driving faster than they really are，and thus drivers slow down.

Now the American Association Foundation for Traffic Safety in Washington D.C. is planning to repeat Japan's success. Starting next year, the foundation will paint chevrons and other patterns of stripes on selected roads around the country to test how well the patterns reduce highway crashes.

Excessive speed plays a major role in as much as one fifth of all fatal traffic accidents, according to the foundation. To help reduce those accidents，the foundation will conduct its tests in areas where speed-related hazards are the greatest-curves，exit slopes，traffic circles，and bridges.

Some studies suggest that straight，horizontal bars painted across roads can initially cut the average speed of drivers in half. However, traffic often returns to full speed within months as drivers become used to seeing the painted bars.

Chevrons，scientists say，not only give drivers the impression that they are driving faster than they really are but also make a lane appear to be narrower. The result is a longer lasting reduction in highway speed and the number of traffic accidents.

4. 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 is unlikely to happen in our lifetime

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

3. What do people think of the suggestion of using nuclear weapons to alter 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 applicable.

2. What do scientists say about the collision of an asteroid with Earth?

　 A) It is very unlikely but the danger exists.

　 B) Such a collision might occur once every 25 years.

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

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

1. 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.

5. When a dog has received effective obedience training, its owner ___________.

　 A) can give the dog more rewards　　　 B) will enjoy a better family life

　 C) can give the dog more freedom　　　 D) will have more confidence in himself

Passage 4

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 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 of the space rocks. By the time we spot a fatal one，the scientists say, we'll have a way to change its course.

　　 Some scientists favor 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 consequences 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 big 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 doomsday (毁灭性的) rocks than from a great nuclear fleet set against them,” said a New York Times article.

4. Why do pet dogs love performing tricks for their masters?

　 A) To avoid being punished.　　　　　　 B) To show their affection for their masters.

　 C) To win leadership of the dog pack.　　 D) To show their willingness to obey.