【简答题】阅读理解 The 2012 London Olympics had enough problems to worry about.But one more has just been added-a communications blackout caused by solar storms. After a period of calm within the Sun, scientists ha...
【简答题】Prehistoric men and women enjoyed a more varied diet(饮食)than people do now, since they ate species(种类)of plant and several hundred thousand types of living things. But only a tiny percentage of these ...