Unit2Building the future构建未来ReadingRenewable energy:a gift for the future可再生能源:给未来的礼物There was once a village surrounded by fertile fields with farmers tending their crops and farm animals grazing lazily below a mighty mountain.Then coal was discovered,and soon titanic-sized earth-digging machines circled the village. Villagers eagerly accepted the high-paid jobs the mining company provided,bringing a temporary economic boom.Meanwhile,the machines cut through everything in their path to access the coal buried beneath.Many years later,all that remained was a deserted village and an enormous hole.从前有一个村庄，四周都是肥沃的田地，农民们在那里照料着他们的庄稼，家畜在巍峨的山下懒洋洋地吃草。
后来，人们发现了煤，很快，巨型挖土机就环绕了整个村子。
村民们急切地接受了矿业公司提供的高薪工作，带来了短暂的经济繁荣。
与此同时，采煤机穿过路上的一切障碍物来开采埋在地下的煤炭。
许多年后，只剩下一个废弃的村庄和一个巨大的洞。
The scenario is tragic,but it only partly describes the damaging effects fossil fuels have on the environment when they are mined.Actually,once burnt,they produce a large quantity of carbon dioxide,which in turn traps heat and causes global warming.Humans are clearly facing a critical moment,so a move towards clean, renewable energy is inevitable.Renewable energy sources,which include solar,wind, hydroelectric,tidal,biomass and geothermal energy,are perfect alternatives to fossil fuels.One of the reasons is that their carbon dioxide emissions tend to be lower.A study found that renewable energy sources emit about50g or less of carbon dioxide per kilowatt-hour over their lifetime,compared to about1,000g for coal.Besides, fossil fuels are non-renewable,whose reserves are estimated to dry up one day in the future.In contrast,renewable energy sources are basically inexhaustible and will be available to us for a few billion more years if our planet remains safe and healthy.这种情况是悲惨的，但它只是部分描述了化石燃料在开采时对环境的破坏性影响。
