首页
外语
计算机
考研
公务员
职业资格
财经
工程
司法
医学
专升本
自考
实用职业技能
登录
外语
Not many of the elements occur in nature as pure substances, lying around waiting for someone to pick them up. A few do, and it
Not many of the elements occur in nature as pure substances, lying around waiting for someone to pick them up. A few do, and it
admin
2010-04-12
159
问题
Not many of the elements occur in nature as pure substances, lying around waiting for someone to pick them up. A few do, and it is not surprising that these were known and collected for various uses in societies around the globe as far back as several thousand years B. C. Sulfur is one of those elements. It was known to burn with smelly results and have an odd appearance. Its use was probably confined to religious ceremonies. Carbon was also known since antiquity, because the charred (烧焦的) bones of animals and portions of partially burned trees consist largely of carbon in the form of charcoal. Although we don’t know all the uses primitive peoples made of charcoal, we do know that it was the key to releasing many other elements from their chemical combination in rocks. For example, if a copper-containing rock was heated in a hot fire with charcoal present, the carbon in the charcoal would combine with the other elements in the rock, leaving free metallic copper. In ways like this people were able to discover the elements copper, iron, lead, tin, and zinc, although they didn’t necessarily appreciate that these substances were elementary. They just knew that they were useful
Iron also arrived occasionally from the heavens in the form of iron-containing meteorites (陨石). Because of this, one might think that iron would have been thought of as a "heavenly" element, a gift from the gods. Instead, this honor has always fallen to the element gold. Gold doesn’t fall from the skies, but it is found in its pure state in some places. It has the unusual property of never tarnishing (锈蚀) like other metals do. Gold objects don’t rust, as iron does, nor do they turn green or black on the surface as do many other metals.
The ancient Egyptians used gold for jewelry and for coins. Gold is still used for jewelry, although pure gold is too soft for this purpose. Coins and jewelry, instead, are made of alloys. These are metals made by melting two or more metals in a pot together in such a way that they dissolve in one another. Gold coins are usually 90 per cent copper. An alloy of gold and silver is called white gold.
The word "instead" in the third sentence of Paragraph 3 suggests______.
选项
A、an example for illustration
B、continuation of the thought
C、more information on a different aspect of the subject
D、a reason for a certain phenomenon
答案
C
解析
该题测试的是篇章知识,需要对上下文作分析。“instead”一般起意义转折作用。第四段开始讲黄金用于做首饰和硬币,紧接着说纯金不宜用于制作首饰。然后另说硬币和首饰是由合金做成的。这里“instead”提示的是将对同一话题提供其它信息。故而选C)。
转载请注明原文地址:https://kaotiyun.com/show/6Nj7777K
0
大学英语四级
相关试题推荐
ExaminationshavealongerhistoryinChinathaninanyothercountry,yetitistodayanissuearoundinwhichcontroversyflou
Ithasbeenprovenmanytimesthatfarmersfarmtheirownlandmorecarefullyandproductivelythantheycultivatesomeoneelse’
Ithasbeenprovenmanytimesthatfarmersfarmtheirownlandmorecarefullyandproductivelythantheycultivatesomeoneelse’
Ithasbeenprovenmanytimesthatfarmersfarmtheirownlandmorecarefullyandproductivelythantheycultivatesomeoneelse’
Ithasbeenprovenmanytimesthatfarmersfarmtheirownlandmorecarefullyandproductivelythantheycultivatesomeoneelse’
随机试题
以下哪项不是恶性肿瘤的晚期表现
《中华人民共和国建筑法》的主要内容包括()。①建筑许可管理;②建筑工程发包与承包管理;③建筑工程监理管理;④建筑安全生产管理;⑤建筑材料管理
积极型管理是有效市场的最佳选择。()
下列关于商业银行会计系统控制的说法中,错误的是()。
在预算周期的环节中,()是整个预算周期的重要环节。
在PowerPoint中,按图所示操作,新幻灯片插入位置是()。
Manypeoplearetiredoftheirjobsandknowtheywanttogivesomethingbacktotheenvironment,buthavenoideawheretolook
最常见的国际资本流动形式是对外直接投资与间接投资,其中对外间接投资包括证券投资、借贷资本输出和()。
TheEuroskepticscontendthattherisksofmonetaryunionfaroutweighanyadvantagesitmaybring.Sinceexchangeratescan(1
Whatdidthemanwant?
最新回复
(
0
)