2016-2017学年 人教版 必修三 Unit 4 Astronomy :the science of the stars grammar课件 (15张)
2016-2017学年 人教版 必修三  Unit 4 Astronomy :the science of the stars grammar课件 (15张)第4页

What does the author want to tell us by the last sentence? “So whether life will continue on the earth for millions of years to come will depend on whether this problem can be solved ”