成因说明:能的来源-Sources of Energy

能的来源
【内容提示】
就下面关于几种能的来源提示写一篇英语文章：
①所有的能都间接或直接地来源于太阳。太阳能两形式：一种是热射线，一种是光射线。以月亮的光为例说明。
②电能以间接的方式来源于太阳，例如它可来自从山腰流下的水的力量。这水就是雨，而雨是由太阳的热蒸发而来的。
③煤里的光能和热能也是间接来自太阳。煤是由树木和其他植物经过千百万年前的岩石挤压形成的，而树木和植物是由于太阳的帮助成长起来的。
④我们用来驱动汽车引擎的能来自汽油。汽油也是由太阳的间接帮助生成的。千百万年前死了的动植物压在岩石下，生成石油，汽油是从石油中提炼出来的。
⑤我们可以说，几乎所有的能都来自太阳；没有太阳地球上就不可能有生命。
【作文示范】
Sources of Energy
Nearly all energy comes from the sun, either in a roundabout① way or straight from it, in the form of heat rays and light rays. The light from the moon, too, comes from the sun. The moon can be said to be like a large mirror which throws back the sun＇s light to the earth.
Electrical energy comes from the sun in a roundabout way, e.g.②, it can come from the power of water falling down a mountainside③. The water fell there as rain, and we know that rain is made by the sun＇s heat evaporating the water on the earth＇s surface. This water vapour rises, condenses④ on cooling, and falls as rain.
The light and heat energy from coal also comes from the sun in a roundabout way. Coal was made by the rocks pressing on trees and plants which died millions of years ago. Those trees and plants grew with the aid of sunlight, from which they made carbohydrates⑤, in this way changing the sun＇s energy into chemical energy. When we burn coal, some of this energy is set free.
Energy which we use to drive car engines comes from petrol⑥,which also was made with the aid of the sun in a roundabout way. Plants, and animals which ate the plants, died millions of years ago, and the parts of them that were left were pressed under the rocks in the 301earth. These parts left from dead animals and plants made petroleum⑦,from which petrol and oil are now obtained.
Thus we can say that the is the place where nearly all energy comes from, and that without the sun＇s heat and light, there could be no life on earth.
（选自《英语学习》1979年第8期）
【词语解释】
①roundabout[＇raund+?baut]a．迂回的；不直接的
②e.g.(拉丁语) exempli gratia的缩写，意为“例如（＝for example）”
③mountainside [＇mauntinsaid] n．山腰
④condense[k+n＇dens] v．使凝结
⑤carbohydrate[＇k%:b+u＇haidreit] n．碳水化合物
⑥petrol[＇petr+l] n．汽油
⑦ petrolem[pi＇tr+ulj+m] n．石油
【写法指要】
本文说明各种能的成因。文章认为，几乎世界上所有的能都以热射线和光射线的形式直接或间接地来自太阳。作者主要分析了四种能，即电、光、热、机械能的来源或成因。最后作者得出结论说，没有太阳的光和热，地球上就不会有生命。