阅读理解

　　Is the world warming up? According to many reports the answer is yes．Eleven of the hottest years since 1850 appeared between 1995 and 2006．Last year, the United Nation’s Intergovernmental Panel on Climate Change(IPCC)reported the earth was about 0.75℃warmer than it was in 1850．While this doesn’t sound like a lot, a small difference in average(平均)temperature can make a big difference in climate(气候)．During the last ice age, the planet was only about five degrees colder than now．

　　It’s all about the speed at which temperatures are changing．In the past, temperatures moved up or down step by step．But in the 20^th century, especially since 1976, temperatures have likely risen more quickly than during any century in the last 1,000 years．Warming may bring improved harvests(收获)to northern countries such as Canada and Russia．However, many species(物种)won’t like these conditions．They begin moving towards cooler places and cause lots of trouble to human world．

　　The IPCC reported that human activity is very likely responsible(负责任的), by increasing the greenhouse effect(效应)．Some gases cause the air to take in heat energy．Without the greenhouse effect, the earth’s average temperature would be -18℃ rather than the present comfortable 14.6 degrees．The main greenhouse gases are carbon dioxide(CO₂), water vapor(蒸汽)and some other gases．Burning oil, coal and waste adds to the Carbon dioxide, and it has increased 35％since 1850．

　　Many researchers have found that natural forces alone don’t explain the temperature increases over the last 30 to 40 years．Their study shows that as carbon dioxide goes up, temperatures will rise too．But some scientists don’t agree．They think the effect of human produced greenhouse gases is very small compared to the normal changes that the climate causes．

　　When asked whether humans are causing the world warming, Carl Wunsch, a professor at the Massachusetts Institute of Technology says,“It seems very likely from what I’ve seen．Is it 100％sure?No．There’s something to do with natural changes．”Does that mean we should have a“wait and see”attitude(态度)?Not according to Wunsch．He points out we buy house insurance(保险)not because we are sure our homes will be on fire, but because it’s a danger we’d rather avoid．

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阅读理解，阅读下面的短文，然后根据短文内容，在每小题所给的四个选项中选出最佳选项。

　　Bicycle tour and race

　　A bike tour and race will be held on August 26th and 27th(Sat．＆Sun．)at 5：30 a．m．The riders will leave Tian’an Men Square and ride the first 35 kilometers as a training leg．Then the next 55 kilometers'leg，from Yanjiao to Jixian，will be the first competitive(比赛的)part of the tour．The riders and their bikes will then be taken from Jixian to Changli．

　　The second racing leg of the tour will be from Changli to the seaside of Nandaihe，covering a distance of 20 kilometers．Saturday night includes the stay at Nandaihe and supper．Sunday morning is free for the seaside．At all the people and their bikes will be taken back to Beijing．

　　Cost：200 yuan Telephone：4675027

　　Brazilian footballers

　　The Brazilian Football Club play Beijjing Guo’an Team at the Workers Stadium On August 26th．The club has four nation team players．Also coming is 1994 US World Cup star Ronario who has promised to play for at least 45 minutes．

　　Ticket Prices：60/100/150 yuan

　　Time/date：4∶30 P．m．August 26th(Sat．)Telephone：5012372

　　Rock climbing

　　The third National Rock Climbing Competition will be held on August 26 th and 27 that the Huairou Mountain-climbing Training Base．More than 10 teams from Beijing，Wuhan，Dalian，Jilin and other places will take part in it．A Japanese team will give an exhibition climbing．Free for audience．

　　Take a long-distance bus from Dongzhimen to Huairou．

　　Time/Date：9～12 am，August 26th and 27th Telephone：7143177，7144850 Wang Zhenghua

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