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　　Ⅰ.篇章结构

　　阅读P23的文章，完成下面表格(每空不超过3个词)

　　 　　Tornadoes 　　Hurricanes 　　What are they？ 　　Tornadoes are rotating columns of air from

　　1． to the ground. 　　Hurricanes are strong 2. storms. 　　Where do they 3. ？ 　　From Texas in the southeast to South Dakota in the north. 　　In the southernAtlantic Ocean，the Caribbean Sea and the Gulf of Mexico. 　　How violent can they be？ 　　The most violent have winds of more than 400 kilometers per hour. 　　There are violent winds of 120 kilometers per hour or more，which 4. huge waves，heavy rains and floods. 　　How often do they occur in the US？ 　　5. ，there are 800 tornadoes in the US each year. 　　There are about six Atlantic hurricanes each year. 　　The worst one 　　It occurred in 1925，6. three US states and killing over 700 people and injuring 2,700. 　　It occurred on the 8th September 1900 in Galveston，Texas，killing 6,000 people and 7.

　　3,600 buildings.