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
Glass is made of mixture of many substances melted together in a large furnace. The most important substance is silica which is
Glass is made of mixture of many substances melted together in a large furnace. The most important substance is silica which is
admin
2014-03-31
41
问题
Glass is made of mixture of many substances melted together in a large furnace. The most important substance is silica which is found in sand. Potash(钾碱), obtained from wood-ashes, is also necessary. To these two substances are added lime, lead, soda and charcoal. Acids are used to remove iron and other impurities. Which might discolor the glass.
The heat of the furnace is so intense that the mixture of these various materials is changed into a boiling liquid. How is liquid glass formed into beautiful or useful objects? Let us imagine that we are watching things being made in a glass factory. It is a small factory in which the work is still done by craftsmen and not by machinery.
Here is a man holding a long iron tube called a blow-pipe. The tube has a wooden mouth-piece to protect the man’s lips from the heat. He puts the other end of the pipe into the molten glass and picks up some of the mixture on the end of the tube. Then he robs the lump of glass to and fro on a metal table, rather like a person rolling pastry. As he rolls it, he shapes the lump roughly into the required form.
Next he lifts the pipe, puts the wooden end to his lips, puffs out his cheeks and blows as you do when you are blowing up a balloon. But of course he has to blow much harder. When the air is blown down into the lump of molten glass a gorge bubble is gradually formed. The craftsman needs both powerful lungs and great skill to ensure that the bubble is of exactly the required size and thickness.
Now you understand why so many hand-made glass objects are round in shape. Handles and feet must be added while the glass is still plastic. When the object is shaped to the craftsman’s satisfaction, it is allowed to cool off. The cooling must be done very gradually. As you know, glass is cracked by extreme and sudden changes of temperature.
Some of the loveliest and many of the most useful things in the world are made of glass. It is most surprising, in view of the great technical skill required, that glass making is a very ancient art. It was practiced thousands of years ago by ancient Egyptians although it was many centuries before men discovered how to make glass transparent.
Glass Making
To remove impurities from the glass,【46】.
Craftsman rolls the molten glass【47】on a metal table.
Glass objects are made【48】.
The mouth-piece of the blow-pipe is【49】.
All glass is【50】.
选项
答案
transparent
解析
转载请注明原文地址:https://kaotiyun.com/show/RzMK777K
本试题收录于:
大学英语三级B级题库大学英语三级分类
0
大学英语三级B级
大学英语三级
相关试题推荐
A、It’sverykindofyou.B、It’swonderful.C、I’m’afraiditcan’twork.D、Noproblem.D“Couldyou…?”是用来询问某种事情的可能性的常见句型,其回答只有肯定和否
Accordingtothepassage,______knowbettertheamazingfunctionsofacellphonethananyone.Fortheteenagers,whatisNOTth
Whenpeoplegetunemployed,whatisoftenworsethanlackofwagesis______.
A、Iwatchedthemovie.B、I’mthinkingaboutthemovie.C、Themovieison.D、itcouldn’tbebetter.D“Whatdoyouthinkof...?”(你
Howmuchdobusticketsforadultscost?______.AtwhattimeisSportandLeisureCenteropen?______.
TheChangjiangRiverisnotthelongest,thewidest,orthemostpowerfulriverintheworld.Butinonesenseitisthemostim
A、Idon’tlikebuttonandbeef.B、Abagoffruitandsomevegetables,please.C、Myfavoritefoodisn’tbreadandbutter.D、Idon
A、Inabank.B、Inabookstore.C、Attheairport.D、Atahotel.D男士想预订双人房间,从Sorry,there’reonlysingleroomsavailable.“抱歉,现在只有单人
Creditcardisbecomingmoreandmorepopular,becauseit’sveryconvenient.Youcantakeittoanywherewithouttakingalotofc
A、Thesametoyou.B、Thankyouverymuch.C、Youmustlikeplayingfootball.D、Infactwedidn’tplayverywell.B本题考查的是对祝贺语的回答。题
随机试题
军种中受双重领导的是_________。
产品结构文件
症见喘促动则为甚,心悸,气短,或咳而气怯,痰多,食少,胸闷,怯寒肢冷,神疲,少腹拘急不仁,脐下动悸,小便不利,足跗浮肿,或吐涎沫而头目昏眩,舌体胖大,质淡。苔白润或腻,脉沉细而滑,宜选用
北京犬,2岁,体表发热,咳声不爽,声音洪大,鼻流黏涕,呼出气热,舌苔薄黄,口色短津,脉象浮数。按照中兽医理论,上述症状属于
论证报告应(),由专家组组长签字,并附每位专家的论证意见。
某单位有107名职工为灾区捐献了物资,其中78人捐献衣物,77人捐献食品。该单位既捐献衣物又捐献食品的职工有()人。
判断一个事物是新事物还是旧事物,最根本的是看这一事物()。
Themanwasundersomuchstressforsuchalongtimethathefinally______.
非物质文化遗产不包括()。
YouwillhearpartofaninterviewbetweenJessiePaul,theglobalmarketingheadinQuintant,andaninterviewer.Foreachques
最新回复
(
0
)