煤-Coal alal is s nl used in life that e seld ntie it e burn al everda t heat fd and ater The first lative as driven b burning al In inter e feel a speial need fr al The al gives us fire, light, heat and arth Industr annt perate ithutl, therefre,ai i9 alled the fd lt industral is nt s treasured as gld Gld is ade int shining rnaents fr the nes f heres and herines al is shining in its n a It burns silentl fr the benefit f all In a sense it is bla gldal underent great hanges befre it beae the bright, brittle, bla substane hih e n use During anient ties, hen the earth ened a ver ar and ist liate, the land as vered ith large frests and big plants As tie ent n, the grund hanged and began t sin These enrus quantities ftrees and vegetable atter ere vered b a depsit f sand and la This laer f sand and la pressed upn the laer beneath and prevented the ntat ith air These trees and plants suued t the pressure and hanged their appearaneGeneratin after generatin, as the grund ept graduall sining, anther laer f sand and la as depsited abve the laers alread fred A great pressure as thus exerted and the peat as hanged int the bla and brittle substane hih is nn as alFr the fratin f al, I see that the al bas the sae harater as the pine trees in inter The pines reain green hen the are vered ith sn The al reains f servie t anind after being burted undergrund fr ears and ears煤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。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。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。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。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。