100.金矿的形成 TW: gold in Wit 1.kw1: 引出gold inWit的独特性,争论:形成过程 2.kw2: shallower gold fields的位置有two rival theories 3.kw3: 关于gold形成人们认同的东西(两个观点认同的) a: 形成时间 b: 形成地点 c: debris沉降 4.kw4: 关于gold从哪里来的争议—two theories a: P—gold deposited at the same time as thepebbles-gold among the debris—all pebble beds b: E—gold arrived several hundred million yearslater-chemical reaction—pebble beds contain iron and other ironbearing rocks nearthe pebbles 5.kw5: E theory—具体的chemicalreaction
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