In Chicago, a computerized system has been developed that controls(管理)traffic on the city’s 235 miles of seven expressways. Now one—a controller—can follow the movement of Chicago’s traffic by looking at a set of lights. The system uses electric sensors(感应器) that are built into each expressway, every half a mile. Several times a second, the computer receives information from each sensor and translates it into green, yellow or red lights on a map in the control room. A green light means traffic is moving forty-five miles an hour, yellow means thirty to forty-five miles an hour, and red means heavy traffic—cars standing still or moving less than thirty miles an hour.

  “See that red light near Austin Avenue?”the controller asked a visitor.“That’s a repair truck fixing the road, and the traffic has to go around it.”At the Roosevelt Road entrance to the expressway, the light kept changing from green to red and back to green again.“A lot of trucks get on the expressway there,”the controller explained.“They can’t speed up as fast as cars.”The sensors show immediately where an accident or a stopped car is blocking the traffic, and a truck is sent by radio to clear the road. The system has lowered the number of accidents by 18 percent. There are now 1.4 deaths on Chicago’s expressway for each one hundred million miles traveled, while in other parts of the county there are 2.6.

  Traffic experts say that the Chicago system is the “coming thing”.Systems like Chicago’s are already in use on some expressways in Los Angeles and Houston.“Chicago has taken the lead,”said New York City’s traffic director and he added,“Chicago’s a good example.”

根据短文内容，选择最佳答案，并在答题卡上按要求作答。

1.The passage is mainly about ________ on expressways in Chicago.

  A. the traffic control system                  B. the movement of the traffic

  C. the electric sensors                       D. the traffic lights

2.When the cars move under 30 miles an hour, ________ on the map in the control room.

A. the red light appears                      B. the red light turns yellow

C. the yellow light appears                   D. the green light turns red

3. According to the passage, we may learn __________.

  A. some visitors are traveling on the expressway

  B. there is no heavy traffic on Chicago’s expressways

  C. the traffic on Chicago’s expressways is well managed

  D. the number of accidents in the US has dropped by 18%

4.In Paragraph 2 the underlined word “it” refers to ___________.

  A. the red light                       B. the truck that needs repairing

  C. the traffic                         D. the truck that is fixing the road

5.The writer writes the article mainly by _________.

  A. giving reasons and results           B. giving examples and explaining them

  C. describing what he thinks          D. asking and answering questions

阅读短文，根据短文内容，从短文后的选项中选出适当的选项补全短文。

What means of transportation do you like? 

Alan 

I find it’s hard to answer this question. I fear (害怕) any kind of transportation, so it’s hard to choose (选择). If I have to, I’d choose the plane .  1.  

Becky

I don’t like taking trains. There are always problems with trains. They’re often late. So I never take a train.  2.    

Sally

  3.    Because I like traveling (旅行) by bicycle, by plane, by boat, by car ... But I like walking best. I enjoy walking. 

Bob

My favorite way of traveling is my computer mouse (鼠标).  4.    I can go around the world in a few minutes.  5.   

A.I use my car and always get where I’m going quickly.

B.It is the fastest means of transportation.

C.I can speak to people from all over the world, and look up (查阅) things quickly too.

D.Answering this question is very difficult.

E.It’s quick, relaxing, and we can get food and drink on the it.

Comets(彗星) are parts of our solar system. Like the planets, they go around the sun.

But comets are not made of solid rocks like planets. A comet is a ball of dust, stones, and ice. Many people call comets dirty snowballs.

The “snowball” may be only a few miles across. But when the sun heats the “snowball,” much of it is changed to gases. The gases spread out and form the comet’s head, which may be thousands of miles across.

A comet moves fast in its trip around the sun. But when we see it, the comet does not seem to move. That’s because it is so far away. The moon moves fast, but when you look at it, you can’t see any motion(运动). That’s because the moon is far away.

Each year astronomers(天文学家) discover new comets. Some of them are seen only once. They make one trip around the sun and then go away out into space. The sun’s gravity cannot hold them.

Other comets, like Halley, keep returning. They have been captured by the sun. Halley’s earliest visit was probably 3,000 years ago. It may keep returning for another 3,000 years.

But every time a comet goes around the sun, the comet loses part of itself. Gases and dust are pulled out of the comet. That’s why Halley is now dimmer（暗淡的） than it used to be. Next time it visits us, in 2062, it may be even dimmer. Each visit it may get dimmer and dimmer, until it finally disappears.

1.What is this passage mostly about?

2.How does the writer help the reader understand what a comet looks like?

3.What is the most likely reason the writer wrote this passage?