45.The source of Energy A summary of the physical and chemical nature of life must begin, not on the Earth, but in the Sun; in fact, at the Suns very center. It is here that is to be found the source of the energy that the Sun constantly pours out i

发表于:2018-11-28 / 阅读(349) / 评论(0) 分类 新概念优美背诵短文50篇