雅思阅读模拟试题学术类（10）

雅思阅读模拟试题学术类（10） 关于这个问题下面小编就来为各个考生解答下。

雅思阅读模拟试题学术类（10） 

D The possibility of losing helium forever poses the threat of a real crisis because

its unique qualities are extraordinarily difficult, if not impossible to duplicate (certainly, no

biosynthetic ersatz product is close to approaching the point of feasibility for helium,

even as similar developments continue apace for oil and coal). Helium is even cheerfully

derided as a “loner” element since it does not adhere to other molecules like its cousin,

hydrogen. According to Dr. Lee Sobotka, helium is the “most noble of gases, meaning

it’s very stable and non-reactive for the most part … it has a closed electronic 12

configuration, a very tightly bound atom. It is this coveting of its own electrons that

prevents combination with other elements’. Another important attribute is helium’s

unique boiling point, which is lower than that for any other element. The worsening

global shortage could render millions of dollars of high-value, life-saving equipment

totally useless. The dwindling supplies have already resulted in the postponement of

research and development projects in physics laboratories and manufacturing plants

around the world. There is an enormous supply and demand imbalance partly brought

about by the expansion of high-tech manufacturing in Asia.

E The source of the problem is the Helium Privatisation Act (HPA), an American

law passed in 1996 that requires the U.S. National Helium Reserve to liquidate its helium

assets by 2015 regardless of the market price. Although intended to settle the original

cost of the reserve by a U.S. Congress ignorant of its ramifications, the result of this fire

sale is that global helium prices are so artificially deflated that few can be bothered

recycling the substance or using it judiciously. Deflated values also mean that natural

gas extractors see no reason to capture helium. Much is lost in the process of extraction.

As Sobotka notes: "[t]he government had the good vision to store helium, and the

question now is: Will the corporations have the vision to capture it when extracting

natural gas, and consumers the wisdom to recycle? This takes long-term vision because

present market forces are not sufficient to compel prudent practice”. For Nobel-prize

laureate Robert Richardson, the U.S. government must be prevailed upon to repeal its

privatisation policy as the country supplies over 80 per cent of global helium, mostly from

the National Helium Reserve. For Richardson, a twenty- to fifty-fold increase in prices

would provide incentives to recycle.

F A number of steps need to be taken in order to avert a costly predicament in the

coming decades. Firstly, all existing supplies of helium ought to be conserved and

released only by permit, with medical uses receiving precedence over other commercial

or recreational demands. Secondly, conservation should be obligatory and enforced by a

regulatory agency. At the moment some users, such as hospitals, tend to recycle

diligently while others, such as NASA, squander massive amounts of helium. Lastly,

research into alternatives to helium must begin in earnest.

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