People and the sources of air pollution are found in the same places. This means that cities with large populations have the biggest problem of dirty air. Air pollution is caused by many different things. A major source of air pollution is the gas fumes from cars. Statistics show that 93 percent of all auto trips are within cities. Another major source of dirty air is the burning of coal and oil for energy. This energy is needed to make electricity. Of course, much more electricity is used in the city than in the country.

　　On the average, we throw away more trash and garbage than the year before. The burning of garbage contributes to air pollution. Many major industries are also responsible for the dirty air in the around cities. The fumes from iron, steel, chemical, and petroleum production add particles to the air.

　　The effects of air pollution range from mild headaches to death. The levels of pollution found in heavy for traffic may cause headaches for loss of clear vision. Wherever coal and oil are used for fuel, fumes may kill trees and plants and cause metal to corrode. In some of the larger cities, these fumes endanger the live of human beings by contributing to lung diseases and causing early death.

　　1. The key point of the passage is that _________.

　　A. the cause of air pollution is people

　　B. the causes and the effects of air pollution are both found in cities

　　C. the effects of air pollution range from headaches to death

　　D. air pollution is caused by dirty air

　　2. What is the purpose of this passage?

　　A. to persuade people to stop polluting the air

　　B. to tell the causes of air pollution

　　C. to tell why cities are bad places to live

　　D. to describe why cities are bad places to live

　　3. Why is air pollution more grave in the city than in the country?

　　A. Because there larger populations in cities.

　　B. Because the air in the city is dirty.

　　C. Because there are more cars in the city.

　　D. Because there are much more gas fumes from cars and burning of coal and oil for energy in the city than in the country.

　　4. The fumes from coal and oil may cause metal ______.

　　A. to turn black B. to become rusty

　　C. to corrode D. to twist

　　5. In larger cities, the fumes from coal and oil may contribute to ___________.

　　A. heart disease B. lung diseases

　　C. loss of clear vision D. serious headache

　　參考答案：

　　1. B。主旨題。縱觀全文，文章的前半部分講的是導致污染的原因，而后半部分講的是污染的結果。而A只強調起因，C只強調結果，D與本文沒有什么關系。所以B為正確答案。

　　2. A。推理題。文章沒有直接說寫這篇文章的目的。但我們從受污染的結果可以推斷出寫這篇文章的目的就是要我們減少污染。所以A為正確答案。

　　3. D。細節題。第一段后半部分說明，空氣污染的主要原因是汽車的廢氣和用來發電的煤和油的燃燒。而汽車和電在城市里比在郊區用得多。故D正確。

　　4. C。細節題。文章最后一段第三句直接提到：wherever coal and oil are used for fuel, fumes may … cause metal to corrode.。所以C為正確答案。

　　5. B。細節題。根據文章最后一句“these fumes endanger the lives of human beings by contributing to lung diseases and causing early death.”可知，B為正確答案。