首页
登录
职称英语
Over the centuries, scientists have been trying hard to find satisfactory su
Over the centuries, scientists have been trying hard to find satisfactory su
游客
2024-08-04
9
管理
问题
Over the centuries, scientists have been trying hard to find satisfactory substitutes for precious stones but failed many times.
Many years ago, a chemist surprised the world by saying: It should be possible to make a precious stone that not only looks like the real thing, but that is the real thing.The only difference should be that one crystal would be made by man, the other by nature.
At first this did not seem like a particularly hard task.
Scientists began to try making synthetic diamonds towards the end of the eighteenth century and discovered a key scientific fact
: diamonds are a form of carbon, which is a very common element.
Then, why not change a cheap and plentiful substance, carbon, into a rare and expensive one, diamond?This change takes place in nature, so it should be possible to make it happen in the laboratory.
It should be possible, but for 150 years every effort failed though several people believed that they had solved the diamond riddle during this period.
The real success came after the scientists realized that, in changing carbon into diamonds, unbelievably heavy pressure and extremely high temperature are indispensable, and carbon needs to be dissolved(溶解) in a metal that helps the reaction to take place more easily.
Under these conditions, a number of shiny crystals were produced in the laboratories of the General Electric Company.The results of careful analysis showed that the chemist was right: these jewels of the laboratory were not like diamonds; they were diamonds. [br] In the 2nd paragraph, what is the chemist trying to say?
选项
A、it is a real thing that man was able to make a precious stone as nature can do.
B、man should be able to make a precious stone that is exactly the same as a natural one.
C、there is only a little difference between a man-made crystal and a nature-made one.
D、scientists expect a small difference between a man-made crystal and a nature-made one.
答案
B
解析
转载请注明原文地址:https://tihaiku.com/zcyy/3705170.html
相关试题推荐
Aspyistryingtosendasecretmessage,we’retryingtodecodehismessage,a
Theneedforasatisfactoryeducationismoreimportantthaneverbefore.No
Theneedforasatisfactoryeducationismoreimportantthaneverbefore.No
Scientistsbelievetheyhavesolvedoneoftheenduringmysteriesofthesex
Scientistsbelievetheyhavesolvedoneoftheenduringmysteriesofthesex
Scientistsbelievetheyhavesolvedoneoftheenduringmysteriesofthesex
Scientistsbelievetheyhavesolvedoneoftheenduringmysteriesofthesex
Scientistsbelievetheyhavesolvedoneoftheenduringmysteriesofthesex
Scientistsbelievetheyhavesolvedoneoftheenduringmysteriesofthesex
Scientistsbelievetheyhavesolvedoneoftheenduringmysteriesofthesex
随机试题
Wewon’tbeabletoleavetheofficeuntiltherain______.A、willstopB、stopsC
[originaltext]ItgoesagainstreligioustaboosinIraqtoinvolvewomenin
设立证券登记结算机构必须经( )批准。A.证券交易所 B.会员大会 C.国
A.八珍丸B.泻毒散C.当归丸D.穿心莲片E.木瓜丸属于处方药的是
国外某研究机构针对网上购物行为进行调查,随机抽取2万名网络购物消费者,对其进行“
《城市道路绿化规划与设计规范》对绿地布局表述不正确的是()。A.种植乔木的
根据罗西的观点,组成城市空间类型的要素是( )。A.城市规模 B.重要纪念物
下列统计指标中,用相对数或平均数形式表现的是()。A:实物指标 B:质量指标
(2016年真题)关于内容效度的说法,错误的是()。A.内容效度主要采用测
某企业为增值税一般纳税人,销售商品适用的增值税税率为13%。2020年10月,自
最新回复
(
0
)