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
2014-08-07
38
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
entirely by machinery
解析
转载请注明原文地址:https://kaotiyun.com/show/JFMK777K
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
Readingnewspapers______.PeopledoallthingswhiletravelingtoworkbytrainEXCEPT______.
Davidhasagreatestproblem.Thatis______.Davidthinkshemightretireearlybecause______.
MyparentsoftentellmethatIoughtto(study)______hard.
说明:请以张华的名义写一封求职信。张华,22岁,毕业于京北职业学院,主修旅游管理,各门课程都优良。已获得导游资格证书。请为她拟出一份给W公司的自荐信,希望能在该公司谋得导游职务。请注意书信的格式。写信的日期为2008年5月10日。Words
说明:假定你是一名大学生,叫李玉(女),月收入在500元以下。于2006年7月5日去超市购物,临走时填了一份问卷调查表。内容如下:1.每月大概光临该超市3次2.对超市的总体管理感到满意3.认为超市工作人员的服务态度很好
Differentcountriesanddifferentraceshavedifferent(11).InChina,itisimportantforthehosttobeattentivetowardst
Herearesomesituationswhererentingmakesmoresensethanbuying.1.Jobuncertainty.Ifyouareaprofessionalworkingwith
DearNancy,NowIamsendingyouacopyofthefinalprogramscheduleoftheConference,togetherwithamapofthelocation
A、Itmattersalot.B、Ifeelrathertiredd.C、Idon’tlikeit.D、Itdoesn’tmatter.B这一句是习惯用语,表达对别人的问候,排除选项,B最合适。
Scientistshavebeentryingtocomeupwithbiologicalexplanationsforthedifferencebetweenboysandgirls.
随机试题
联言判断的命题形式是:()。
四项基本原则和改革开放相互贯通、相互依存。()
A.忧郁B.退化C.猜疑D.期待E.焦虑
根据《商标法》规定,商品的商标未经核准注册的,该商品()。
2016年9月15日,甲材料供应商与丙材料供应商订立书面合同,转让甲对乙施工企业的30万元债权。同年9月25日,乙接到甲关于转让债权的通知。关于该债权转让的说法,正确的是()。
关于生产要素国际移动机制的说法中,错误的是()。
根据《期货交易管理条例》,()的工作人员,应当忠于职守,依法办事,公正廉洁,保守国家秘密和有关当事人的商业秘密,不得利用职务便利牟取不正当的利益。[2014年3月真题]
行政处罚是公安机关行使的重要执法权。处罚裁量是否合理、适当,直接影响当事人权益。根据合理性原则,民警在办理行政案件时,认为下列情形属于“情节较轻”的是()。
A、 B、 C、 D、 D从第一个图形开始,每条竖线同时向右移动得到下一个图形,移动的步数依次为1、2、3、4。故本题选D。
Whichofthefollowingisnotaplacewheremostoriginalclassicalmusicwaswritten?
最新回复
(
0
)