5. C。推断题。根据 However, traffic often returns to full speed within months as drivers become used to seeing the painted bars 可知。

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The common cold is the world's most widespread illness, which is plagues(疫病) that flesh receives.

The most widespread mistake of all is that colds are caused by cold. They are not. They are caused by viruses(病毒) passing on from person to person. You catch a cold by coming into contact, directly or indirectly, with someone who already has one. If cold causes colds, it would be reasonable to expect the Eskimos to suffer from them forever. But they do not. And in isolated Arctic regions explorers have reported being free from colds until coming into contact again with infected people from the outside world by way of packages and mail dropped from airplanes.?

During the First World War soldiers who spent long periods in the trenches(战壕), cold and wet, showed no increased tendency to catch colds.?

In the Second World War prisoners at the notorious Auschwitz concentration camp(奥斯维辛集中营), naked and starving, were astonished to find that they seldom had colds.?

At the Common Cold Research Unit in England, volunteers took part in Experiments in which they gave themselves to the discomforts of being cold and wet for long stretches of time. After taking hot baths, they put on bathing suits, allowed themselves to be with cold water, and then stood about dripping wet in drafty room. Some wore wet socks all day while others exercised in the rain until close to exhaustion. Not one of the volunteers came down with a cold unless a cold virus was actually dropped in his nose.?

If, then, cold and wet have nothing to do with catching colds, why are they more frequent in the winter? Despite the most pains―taking research, no one has yet found the answer. One explanation offered by scientists is that people tend to stay together indoors more in cold weather than at other times, and this makes it easier for cold viruses to be passed on.?

No one has yet found a cure for the cold. There are drugs and pain suppressors(止痛片) such as aspirin, but all they do is to relieve the symptoms(症状).?

4. A。细节题。 根据paint chevrons and other patterns of stripes on selected roads around the country，可知他们在精心挑选的几条路上试验日本的模式。

3. D。推断题。由最后两段对比可知，人字形线比直线、平等线对控制车速有更长久的影响。

2. C。细节题。由But 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.可知C项正确。

1. A。主旨题。通读全文，我们可以知道，在高速公路上画各种线是为了让司机觉得车速过快，从而达到控制车速的目的。

5. What does the author say about straight, horizontal bars painted across roads?

A. They are suitable only on broad roads.     

B. They are falling out of use in the United States.

C. They are ignored in a long period of time.

D. They cannot be used successfully to traffic circles.

【答案解析】为了控制车速，减少交通事故，美国决定在公路上画人字形标志。

4. The American Automobile Association Foundation for Traffic Safety plans to ________.

A. try out the Japanese method in certain areas

B. change the road signs across the country

C. replace straight, horizontal bars with chevrons

D. repeat the Japanese road patterns

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 look more attractive   D. will have a longer effect on drivers

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 coming near to 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 way of training drivers

D. a new type of optical illusion