下面是阅读理解原文,有一道题做错了不明原因,It is only a shiny,yellow metal,but it is one of the most valuable metals on earth.Since the beginning of time,men have looked for this extremely valuable item,gold.Gold is soft and easy t

下面是阅读理解原文,有一道题做错了不明原因,It is only a shiny,yellow metal,but it is one of the most valuable metals on earth.Since the beginning of time,men have looked for this extremely valuable item,gold.Gold is soft and easy t
下面是阅读理解原文,有一道题做错了不明原因,
It is only a shiny,yellow metal,but it is one of the most valuable metals on earth.Since the beginning of time,men have looked for this extremely valuable item,gold.
Gold is soft and easy to form into different objects.If it gets wet,it does not rust like iron or other metals.Acids do not change it.One important reason that gold is so valuable is that it is scarce.
Due to its softness,gold must be combined with other metals to harden it and give it strength.By hardening gold,people can then make coins and jewelry with it.Metals commonly mixed with gold are nickel,platinum,and copper.Gold jewelry bears a number and the letter K.The K means karat (carat),which is a measure of the amount of pure gold in the jewelry.Pure gold is 24K.Therefore,a necklace which is 14K is fourteen parts gold and ten parts other metal.
Many countries utilize gold for certain coins,but this practice is not as common now as it once was.The United States,for instance,stopped making gold coins in 1933.
答题：59.If a ring is marked 12K,then the percentage of gold in it is _____.
A.12 B.50 C.25 D.24
答案给的是B.50k,不知道为什么选B,50是怎么计算出来的

下面是阅读理解原文,有一道题做错了不明原因,It is only a shiny,yellow metal,but it is one of the most valuable metals on earth.Since the beginning of time,men have looked for this extremely valuable item,gold.Gold is soft and easy t
啊,关键在这里啊 “ Pure gold is 24K.Therefore,a necklace which is 14K is fourteen parts gold and ten parts other metal“,意思是说,纯金是24k,所以如果项链是14k,就说明有14/24是金,10/24是其他金属.
再看题目,如果是12k,带入上文,自然说明含金量是12/24了,于是得出50%.
我讲的清楚吧,mm的名字是岳灵珊哈,是我最喜欢的金庸女性了..