上学期unit9warmingupandlistening课件
日期：2010-02-23 02:22
Unit 9 Saving the earth
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What is the biggest problem facing the earth?why do you think so?
Air pollution
What causes the problem? What can we do to solve the problem?
desertification
Why is more and more land becoming desert?
1:03 结束
a vedio，
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