People have valued gold for thousands of years. The soft, dense metal polishes to a bright yellow shine and resists most chemical reactions.人们重视黄金价值已有数千年历史，这种质地柔软密度大的金属闪耀着亮黄色光芒，能抵抗大部分化学反应。
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It makes a good material for money 、political power and more recently electric power .If you own the // like a mobile phone or a computer ,you might own a little gole on the // .作者: gqinchunh123 时间: 2012-5-13 17:53
继续努力学习作者: jiaoyangrenshen 时间: 2012-6-25 19:57
Also, organic farmers can improve their yields by making sure their crops get enough fertilizer. But increasing the nitrogen is harder to do organically, using just animal waste and crop rotations. Organic farmers rotate food crops with plants that fertilize the soil.此外，有机农民可以给作物施足量的肥料以提高产量，但仅仅使用动物粪便和作物轮作这种方式增加氮量很难。有机农民将粮食作物与能肥田的作物轮作。
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But while these "cover," or fertilizer, crops are growing, food crops have to be grown on other land. And if farmers use manure, they have to feed the animals that produce it, and that requires grazing land or crop land.但种植这些肥料作物时，就只能在其它地里种植粮食作物。如果农民使用粪肥，就必须喂养产生粪肥的动物，这就需要牧场和耕地。
