出版时间:2009-7 出版社:高等教育出版社 作者:潘晓燕 页数:260
内容概要
根据2009年大学英语六级考试最新趋势设计的8套模拟试卷,附听力光盘、答题卡、听力录音稿和题目精解。
书籍目录
大学英语六级考试模拟试卷一大学英语六级考试模拟试卷二大学英语六级考试模拟试卷三大学英语六级考试模拟试卷四大学英语六级考试模拟试卷五大学英语六级考试模拟试卷六大学英语六级考试模拟试卷七大学英语六级考试模拟试卷八大学英语六级考试模拟试卷九
章节摘录
Non-ferrous metals Aluminum is shredded and ground into small pieces or crushed into bales.These pieces or bales are melted in an aluminum smelter to produce molten aluminum.By this stage the recycled aluminum is indistinguishable from virgin aluminum and further processing is identical for both.This process does not produce any change in the metal,SO aluminum can be recycled indefmitely. Recycling aluminum saves 95%of the energy cost of processing new aluminum.This is because the temperature necessary for melting recycled,nearly pure,aluminum is 600℃。while to extract mined aluminum from its ore requires 900 oc.To reach this higher temperature,much more energy is needed,leading to the high environmental benefits of aluminum recycling.Glass Glass bottles and jars are gathered via eurbside(路边)coHection schemes and bottle banks.where the glass may be sorted into color categories.The collected glass cullet(碎玻璃)is taken to a glass recycling plant where it is monitored for purity and contaminants are removed.The cullet is crushed and added to a raw material mix in a melting furnace.It is then mechanically blown or mold.ed into new jars or bottles.Glass cuHet is also used in the construction industry for aggregate(集料)and glassphalt.Glassphalt is a road—laying material which comprises around 30%recycled glass.Glass can be recycled indefinitely as its structure does not deteriorate when reprocessed.
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