新視野大學(xué)英語視聽說教程第三冊(cè) Unit 7 Task 2: A Work Qualification Test

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According to a report by Australian researchers, the hole in the ozone layer over Antarctica will probably start closing within five years. They say it may be completely closed within fifty years. The ozone layer protects the Earth from dangerous radiation from the sun. The hole in the ozone layer was discovered over Antarctica almost thirty years ago. At the time, it was three times the size of Australia.

The report found that ozone-destroying gases in the upper atmosphere were at or near their highest levels in the year2000. But since then, there has bee continuous progress made toward the recovery of the ozone layer.

Satellite information showed that levels of ozone-destroying gases in the atmosphere are slowly decreasing. At its largest this year, the ozone hole covered more than 15 million square kilometers. That is down from a yearly average of 23 million square kilometers over the last six years.

Chlorofluorocarbons, or CFCs, are responsible for destroying part of the ozone layer over Antarctica. CFCs have been widely used since the1930s in cooling devices such as refrigerators and air conditioners. CFCs remain in the atmosphere for years.

Government scientist say the level of chlorine in the atmosphere is decreasing because ofrestrictions on the use of chlorofluorocarbons. The chemicals were restricted under an international agreement called the Montreal Protocol in 1987. Under the Protocol, developing countries promoted to cut their use of chlorofluorocarbons in half by the year 2005. They also agreed to an eighty-five percent cut by the year 2oo7.

Keys: FTTFT

For Reference

1. It was three times the size of Australia.

2. They promised to cut their use of CFCs in the half by 2005 and agreed to an 85 percent cut by 2007.