1．In Chicago，a computerized system has been developed that controls（管理）traffic on the city's 235miles 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 18percent．There are now 1.4deaths 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．
66．The passage is mainly aboutA on expressways in Chicago．
A．the traffic control system B．the movement of the traffic
C．the electric sensors D．the traffic lights
67．When the cars move under 30miles an hour，A 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
68．According to the passage，we may learnC．
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%
69．In Paragraph 2the underlined word"it"refers toD．
A．the red light B．the truck that needs repairing
C．the traffic D．the truck that is fixing the road
70．The writer writes the article mainly byB．
A．giving reasons and results B．giving examples and explaining them
C．describing what he thinks D．asking and answering questions．
分析 本文介绍了美国芝加哥用电脑系统如何管理城市的高速公路．
解答 66．A 大意理解题．根据文章第一段In Chicago，a computerized system has been developed that controls（管理）traffic on the city's 235miles of seven expressways大意可知这篇文章主要介绍了在芝加哥高速公路上的交通控制系统，故选A．
67．A 细节理解题．根据文章第一段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．绿灯意味着交通每小时行驶四十五英里，黄色意味着每小时三十到四十五英里，红色意味着重型交通车静止不动或每小时移动不到三十英里．故选A，the red light appears．
68．C 理解推断题．根据第二段和第三段的大意可知在芝加哥高速公路的交通被很好的管理．因此选C．
69．D 理解推断题．根据上文That's a repair truck fixing the road那是修理公路的修理车，可知此处应该是：and the traffic has to go around it．车辆必须绕过它．可知此处it代替"the truck that is fixing the road"．故选D．
70．B 理解推断题． 根据，"Chicago's a good example．"芝加哥是一个很好的例子．可知作者是通过举例子讲事实来写这篇文章的．故选B．
点评 做题时要在理解好文意的基础上，与题目有机的结合，从文章中找到相关细节性的句子与选项细细比对，进行选择或推理判断，选出符合文章内容的正确选项．做题注意灵活，有时可采用排除法或直选法确定出最终答案．
