四六级考试

【单选题】
A、Because their value has been raised since they were made.

B、Because they contain more silver than they used to.
C．Because they contain less silver than they should do.
D．Because the metal wears down in use.

网考网参考答案：C
网考网解析：
[听力原文]29-32 A silver dollar is not worth a dollar--nor is any other silver coin really worth its face value. Silver coins are made of an alloy--a mixture of 10 per cent copper and 90 per cent silver---which lasts much longer in circulation than pure silver would. A silver dollar contains 90 cents worth of silver and a dime has 9 cents worth. It takes only a pennyworth of silver to make a nickel. This was not the case in 1792, when the United States began minting coins of pure gold and silver. Citizens were welcome to stop in anytime with gold or silver in any form--cups, vases, or even gold fillings from their teeth--and have it melted down for spending money. Today the mints in Philadelphia and Denver earn a yearly profit of about ＄40 million. Most of this comes from using alloys rather than pure silver in the production of the ＄2.5 billion worth of coins circulating in the United States. The Philadelphia plant also manufactures coins for foreign countries. In a recent year almost 130 million coins were made for the use of foreign governments. 29: Why are silver coins today not worth their face value 事实细节题 文章明确说明了当今的银币是由合金铸成的，已经不是从前的纯银币了。 document.getElementById("warp").style.display="none"; document.getElementById("content").style.display="block"; 查看试题解析出处>>