（第二版）全新版大学英语综合教程4Unit2课后答案

　　II.

　　3. 1) There was an unusual quietness in the air, except for the sound of artillery in the distance.

　　2) The expansion of urban areas in some African countries has been causing a significant fall in living standards and an increase in social problems

　　3) The research shows that atmospheric carbon dioxide levels are closely correlated with

　　global temperatures

　　4) The frequency of the bus service has been improved from 15 to 12 minute recently.

　　5) The diver stood on the edge of the diving board, poised to jump at the signal from the coach.

　　4. Automobiles have, since their invention, revolutionized transportation, changing forever the way people travel, and do

　　business. On the other hand, they have brought hazards, especially highway fatalities. However, today the application of computer technology and electronic sensors in designing and manufacturing cars makes it possible to eliminate most of traffic accidents. For example, electronic sensors mounted in your car can detect alcohol vapor in the air and refuse to start up the engine. They can also monitor road conditions by receiving radio signals sent out from orbiting satellites and greatly reduce your chances of getting stuck in traffic jams.

　　Text B

　　Comprehension Check

　　2. a c c d b b

　　Translation

　　5. 这类系统易受气候变化的`影响，提供的数据不够精确，但他们不需要特别的道路设施，只需要将车道标志维护好

　　就行了。

　　6. 然而，不用多久，其成本就能为广大车辆拥有者和驾驶者所接受，尤其是目前不少可以应用的技术已经走向市场，

　　开始了批量生产。

　　7. 电子驾驶应用的最大障碍可能在于人们普遍认为认为这一技术的应用比实际情况更困难，更昂贵。

　　8. 考虑到这些运用安全自动化交通运输系统的经验，开发由自动控制系统操纵的公路车辆算不上什么大的飞跃。 Language Practice

　　3. c a e b f g d h

　　4. 1) en route 2) matures 3) equivalent 4) feasible 5) in cooperation with 6) exposure