北京新航道为大家提供托福培训，解决托福各方面的难题。我们都知道，托福阅读题量大，时间紧迫，所以说事先掌握的背景知识有利于自己做题的速度和效率。遇到难句难文也有理据去猜测一下。下面就由北京新航道的小编为大家奉上精心整理的一些有助于阅读的背景知识。

　　polymer gels一种聚合凝胶

　　The following information was part of our display for the SET96 and SET98 Scientific Power to the People Exhibition, The Galleries, Bristol, 20th and 21st March 1998.

　　A POLYMER is a very long molecule rather like a very long piece of string.

　　The borax joins two molecules together to make a large network - rather like a flexible scaffolding. This is cross-linking.

　　This turns the fluid dissolved polymer into a GEL.来源：北京新航道托福培训

　　In oilwells water is pushed down to push oil up. If this breaks through to the production well bore, the well will just produce water. A solution is to block the rock pores with polymer gel to make the well produce oil again. These gels can be made from naturally occurring sugar-based polymers such as Guar and they can be cross-linked with Cobalt or Chromium.

　　Other everyday examples of polymer gels are to be found in non-drip emulsion paints, foods, car tyres and agrochemicals.

　　The polymer that we are using is POLYVINYL ALCOHOL and we are joining the strands together with BORAX. This gel, when coloured, is sold in toyshops as SLIME.

　　上面是一些实用的阅读背景知识，希望大家能够看一看，理解一下。在真正的考试过程中极有可能会用到。了解的北京对于做好阅读有很大的帮助。希望各位同学都能够取得理想的成绩。

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