精选优质文档-倾情为你奉上一、阅读理解(共20题，合计100分)Unit 1Passage One Carbon dioxide makes up less than one percent of the Earths atmosphere, but the gas is very important to life on Earth. Scientists are finding that processes involving carbon dioxide affect our climate in ways that are difficult to understand. Last month, a committee of the National Academy of Sciences in Washington released a report. It confirmed that world temperatures increased about six-tenths of a degree Celsius in the last one
