当前位置:首页 → 职业资格 → 教师资格 → 中学英语学科知识与教学能力->请阅读短文,完成此题。Polyester(聚酯)isnowb
请阅读短文,完成此题。
Polyester (聚酯 ) is now being used for bottles. ICI, the chemicals and plastics company, believes that it is now beginning to break the grip of glass on the bottle business and thus take advantage of this huge market.
All the plastics manufacturers have been experiencing hard times as their traditional products have been doing badly world-wide for the last few years. Between 1982 and 1984 the Plastics Division of ICI had lost a hundred and twenty million dollars, and they felt that the most hopeful new market was in packaging, bottles and cans.
Since 1982 it has opened three new factories producing "Melinar", the raw material from which high quality polyester bottles are made.
The polyester bottle was born in the 1970s, when soft drinks companies like Coca Cola started selling their drinks in giant two-liter containers. Because of the build-up of the pressure of gas in these large containers, glass was unsuitable. Nor was PVC, the plastic which had been used for bottles since the 1960s, suitable for drinks with gas in them. A new plastic had to be made.
Glass is still cheaper for the smaller bottles and will continue to be so, unless oil and plastic become much cheaper, but plastic does well for the larger sizes.
Polyester bottles are virtually unbreakable. The manufacturers claim they are also lighter, less noisy when being handled, and can be reused. Shopkeepers and other business people are unlikely to object to a change from glass to polyester, since these bottles mean few breakages, which are costly and time-consuming. The public, though, have been more difficult to persuade. ICI's commercial department is developing different bottles with interesting shapes, to try and make them visually more attractive to the public.
The next step could be to develop a plastic which could replace tins for food. The problem here is the high temperatures necessary for cooking the food in the container.
Plastics of va
根据第四段“Nor was PVC,the plastic which had been used for bottles since the 1960s.suitable for drinks with gas in them."可知,作为“plastics of various kinds”中的一种,PVC在1960s就已用于瓶子包装,因此可以判断“plastics of various kinds”在1960s就已用于瓶子包装。
《义务教育数学课程标准(2011年版)》强调,课程内容要反映社会的需要、数学的特点,要符合学生的认知规律。课程内容的组织要重视过程,处理好()的关系。
设α是某一方程组的解向量,k为某一常数,则kα也为该方程组的解向量。( )
案例:
在有理数运算的课堂教学片段中,某学生的板演如下:
针对该学生的解答,教师进行了如下教学:
师:请仔细检查你的演算过程,看是否正确无误?
生:好像正确吧。
请分析例题1、例题2中每一步运算的依据。(10分)
初中数学课程是一门国家课程,其主要内容包括课程目标、教学内容、教学过程和( )等
教师职业道德区别于其他职业道德的显著标志就是( )。
对高中数学的评价,下列说法错误的是( )。