题目

　　In the middle of winter, when snow is falling in many parts of the United States, scientists have sounded a warning to people who plan to spend many hours in the sun this summer．The warning is：The sun's summertime rays(射线)are more dangerous than once thought．　　A team of scientists from 80 nations recently reported to the United Nations that a layer of ozone(臭氧层)in the atmosphere(大气)，which protects humans from harmful levels of ultraviolet(紫外线)radiation(放射)，will be thinner over the United States this summer．The thinner layer allows more ultraviolet rays from the sun to reach the earth．The extra amount of ultraviolet radiation could cause an increase in the number of cases of skin cancer(癌症)．　　Scientists first became concerned about the ozone layer in the mid 1980s when a hole was discovered in the layer above Antarctica during the winter．The hole was caused by chemicals used in refrigerators(冰箱)and air conditioners．When these chemicals are sent out into the atmosphere, they produce gases that destroy the ozone．　　Concern about the protective ozone layer rose more recently when data(数据) from satellites and ground stations showed that ozone levels were dropping over areas other than Antarctica．Low ozone levels were recorded in the spring and summer over the United States and over other populated areas in the world．Although many countries have already begun stopping the use of ozone-destroying chemicals, the new findings are expected to advance the timetable for a total ban(禁止)of the chemicals． (1) The scientists have observed the ozone layer ． [　　] A． since 1980 B． since last winter C． for about 20 years D． for about one year (2) The ozone layer in the atmosphere can ． [　　] A． do a lot of good to human beings in many ways B． protect human beings from disease caused by bad weather C． do a lot of harm to human beings in the summertime D． protect human beings from harmful levels of ultraviolet radiation (3) The damage to the ozone layer was caused by ． [　　] A． the changeable weather B． ozone destroying chemicals C． chemicals from refrigerators D． chemicals from air conditioners (4) Which of the following is NOT true? [　　] A． The use of ozone destroying chemicals has already been stoppeD． B． The ozone levels in the spring and summer over the US were low． C． More and more people have begun to protect the nature surroundings． D． Many countries have already taken measures to protect the layer．

　　In the middle of winter, when snow is falling in many parts of the United States, scientists have sounded a warning to people who plan to spend many hours in the sun this summer．The warning is：The sun's summertime rays(射线)are more dangerous than once thought．

　　A team of scientists from 80 nations recently reported to the United Nations that a layer of ozone(臭氧层)in the atmosphere(大气)，which protects humans from harmful levels of ultraviolet(紫外线)radiation(放射)，will be thinner over the United States this summer．The thinner layer allows more ultraviolet rays from the sun to reach the earth．The extra amount of ultraviolet radiation could cause an increase in the number of cases of skin cancer(癌症)．

　　Scientists first became concerned about the ozone layer in the mid 1980s when a hole was discovered in the layer above Antarctica during the winter．The hole was caused by chemicals used in refrigerators(冰箱)and air conditioners．When these chemicals are sent out into the atmosphere, they produce gases that destroy the ozone．

　　Concern about the protective ozone layer rose more recently when data(数据) from satellites and ground stations showed that ozone levels were dropping over areas other than Antarctica．Low ozone levels were recorded in the spring and summer over the United States and over other populated areas in the world．Although many countries have already begun stopping the use of ozone-destroying chemicals, the new findings are expected to advance the timetable for a total ban(禁止)of the chemicals．

(1)

The scientists have observed the ozone layer ________．
[　　]
A．	since 1980
B．	since last winter
C．	for about 20 years
D．	for about one year

(2)

The ozone layer in the atmosphere can ________．
[　　]
A．	do a lot of good to human beings in many ways
B．	protect human beings from disease caused by bad weather
C．	do a lot of harm to human beings in the summertime
D．	protect human beings from harmful levels of ultraviolet radiation

(3)

The damage to the ozone layer was caused by ________．
[　　]
A．	the changeable weather
B．	ozone destroying chemicals
C．	chemicals from refrigerators
D．	chemicals from air conditioners

(4)

Which of the following is NOT true?
[　　]
A．	The use of ozone destroying chemicals has already been stoppeD．
B．	The ozone levels in the spring and summer over the US were low．
C．	More and more people have begun to protect the nature surroundings．
D．	Many countries have already taken measures to protect the layer．

题目解答

答案

1．C;2．D;3．B;4．A;

解析

步骤 1：确定科学家观察臭氧层的时间
根据文章，科学家们在1980年代中期开始关注臭氧层，因为那时在南极洲上空发现了臭氧层空洞。因此，科学家们观察臭氧层的时间大约为20年。
步骤 2：确定臭氧层的功能
臭氧层在大气中保护人类免受有害的紫外线辐射。因此，臭氧层的功能是保护人类免受有害的紫外线辐射。
步骤 3：确定臭氧层受损的原因
臭氧层受损的原因是使用了破坏臭氧的化学物质，这些化学物质在冰箱和空调中使用。这些化学物质释放到大气中，会产生破坏臭氧的气体。
步骤 4：确定哪一项陈述是不正确的
根据文章，许多国家已经开始停止使用破坏臭氧的化学物质，但并没有完全停止。因此，选项A是不正确的。