煤-Coal

　　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.

　　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.

　　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.

　　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 eerted and the peat was changed into the black and brittle substance which is known as coal.

　　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.

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