煤-Coal

煤-Coali7F易文君-文库范文网

　　Coali7F易文君-文库范文网

　　Coal is so commonly used in life that we seldom notice it. We burn coal everyday to heat food and water. The first locomative was driven by burning coal. In winter we feel a special need for coal. The coal gives us fire, light, heat and warmth. Industry cannot operate withoutcml, therefore,mai i9 called the food lot industry.i7F易文君-文库范文网

　　Coal is not so treasured as gold. Gold is made into shining ornaments for the necks of heroes and heroines. Coal is shining in its own way. It burns silently for the benefit of all. In a sense it is black gold.i7F易文君-文库范文网

　　Coal underwent great changes before it became the bright, brittle, black substance which we now use. During ancient times, when the earth enjoyed a very warm and moist climate, the land was covered with large forests and big plants. As time went on, the ground changed and began to sink. These enormous quantities oftrees and vegetable matter were covered by a deposit of sand and clay. This layer of sand and clay pressed upon the layer beneath and prevented the contact with air. These trees and plants succummed to the pressure and changed their appearance.i7F易文君-文库范文网

　　Generation after generation, as the ground kept gradually sinking, another layer of sand and clay was deposited above the layers already formed. A great pressure was thus exerted and the peat was changed into the black and brittle substance which is known as coal.i7F易文君-文库范文网

　　From the formation of coal, I see that the coal bas the same character as the pine trees in winter. The pines remain green when they are covered with snow. The coal remains of service to mankind after being burted underground for years and years.i7F易文君-文库范文网

　　煤i7F易文君-文库范文网

　　煤在生活中用得如此普遍，以至于我们很少注意到它。我们每天烧煤做饭、烧水。第l辆火车是用燃煤的方法开动的。冬天我们特别需要煤。煤给我们火、光、热和温暖。工业离不开煤，因此，煤被称为工业的食粮。i7F易文君-文库范文网

　　煤不像金子那么贵重，金子用来做装饰品，挂在英雄的脖子上，然而煤以它自己的方式闪光。为了大家的利益，它无声地燃烧。在某种意义上，煤是黑色的金子。i7F易文君-文库范文网

　　煤经历了巨大的变化才变成亮、脆而黑的物质供我们使用。在古代，地球经历了温暖、潮湿的气候，土地被大片的森林和高大的植物所覆盖。随着时间的流逝，地面下陷，大量的树木、植物类的物质受到泥沙的覆盖。这层泥沙压在植物层之上，使它不能与空气接触。这些树木、植物由于受到压力而变形。i7F易文君-文库范文网

　　经历了多少代又多少代，随着地面不断地渐渐下陷，又有另一层泥沙覆盖在已经形成的泥沙层上，因而产生巨大的压力，泥炭便变成又黑又脆而被称作煤的物质。i7F易文君-文库范文网

　　从煤的形成中可以看出，煤具有冬天里松树的性格。松树被雪覆盖时，仍然保持碧绿；煤被埋在地下多少年又多少年，仍然在为人类服务。i7F易文君-文库范文网