【编者按】精品学习网英语四六级频道为大家收集整理了“2012英语六级阅读练习：灰尘背后的那些事儿”供大家参考，希望对大家有所帮助!
六级阅读理解题型的同学应该都了解，英语四六级考试阅读理解材料大多选自《时代》《卫报》《科学美国人》等外刊。要想阅读理解这部分拿到高分，必须在平常多阅读，掌握新词汇，锻炼阅读速度。但对于很多同学来说，如何每日在浩瀚的互联网世界寻找合适的阅读材料进行分析解读是一项很耗时间的事情。为此，考试大英语四六级站点每日精选《卫报》《时代》等外刊上的文章供大家进行阅读练习。
【今日阅读推荐】本篇阅读材料“灰尘背后的那些事儿”选自《时代》(原文标题：What’s in Household Dust? Don’t Ask 2010.2 23)。如果大家觉得比较简单，就当作泛读材料了解了解，认识几个新单词或新表达方式也不错。如果大家觉得这些材料理解上有难度，不妨当做挑战自己的拔高训练，希望大家都有进步^^
It’s hard to get too worked up about dust. Yes, it’s a nuisance, but it’s hardly one that causes us much anxiety — and our language itself suggests as much. We call those clumps of the stuff under the bed dust bunnies after all, not, say, dust vermin.
to get worked up 为某件事生气;不开心
clumps of 一团一团的
dust bunny 积尘;灰兔子(关于灰尘的比较萌的说法)
But there’s a higher ick factor to dust than you might think. And there’s a science to how it gets around — a science that David Layton and Paloma Beamer, professors of environmental policy at the University of Arizona, are exploring.
get around 传播;散播
Layton and Beamer, whose latest study has been accepted for fall publication in the journal Environmental Science & Technology, knew a lot about their subject even before they set to work. Historically, everyone from chemists to homemakers has tried to figure out just what dust is made of, and the Arizona researchers drew their preliminary data mostly from two studies of household dust conducted in the Netherlands and the U.S. The American survey in particular was a big one, covering six Midwestern states. Layton and Beamer also included a localized study in Sacramento, Calif., that focused particularly on lead contamination. What all those surveys showed was decidedly unappetizing.
figure out 理解;解决;计算
The specific dust mix in any household differs according to climate, age of the house and the number of people who live in it — not to mention the occupants’ cooking, cleaning and smoking habits. But nearly everywhere, dust consists of some combination of shed bits of human skin, animal fur, decomposing insects, food debris, lint and organic fibers from clothes, bedding and other fabrics, tracked-in soil, soot, particulate matter from smoking and cooking, and, disturbingly, lead, arsenic and even DDT.
"There are more [components]," Beamer says. "Dust is a hodgepodge of all sorts of things. It would probably be impossible to make a list of all the possible items."
But dust’s ingredient label is not the whole story, since all of those flecks and bits behave differently and present different levels of health risk. To investigate those factors more closely, Layton and Beamer developed a computer algorithm that looked at the size, source and toxicity of dust particles as well as how easily they enter the house, if they ever exit and, if so, by what route. That information, by extension, can provide at least a rough sense of the dust load in your own home.
As a general rule, the majority of household dust — about 60% — comes from outside, through windows, doors, vents and, significantly, on the soles of your shoes. Smaller dust particles — from 28 to 49 microns, or thousandths of a millimeter — tend to stay on your shoes. The rest is shaken off inside. A higher share of the dust that floats in the air gets deposited, but again, there’s a lot that determines how much any one home will get.
"Here in Arizona," says Beamer, "where we leave our windows open most of the year and have an arid climate, we would probably have a higher ratio." Industrial centers or sooty cities have plenty of dust too, though for different reasons.
arid adj. 干旱的;不毛的
ratio n. 比例
There’s not much to fret about in simple particles of dirt or organic materials such as pollen (though they can trigger allergies), but lead, arsenic and DDT can be a more serious matter. About one-third of the arsenic in the atmosphere comes from natural sources — volcanoes principally. The rest comes from mining, smelting, burning fossil fuels and other industrial processes. Even in relatively low concentrations, arsenic is not without risk, especially to small children who play on the floor and routinely transfer things from their hands to their mouths. The same is true for lead, which comes less from wall paint — the source most people would expect — than from auto exhaust, smelting and soil deposits. "Lead loading on floors is a key determinant of blood-lead levels in children," Layton and Beamer wrote in their paper.