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《考研英语阅读理解100篇 基础版》第7章 医药类 Unit 91

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2019年01月21日

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IF YOU’RE CONFUSED BY ALL the news about the health effects of eating fish,you’re not alone.On one hand,the omega-3 fatty acids in fish are known to reduce the risk of heart disease,as the American Heart Association reminded us two weeks ago when it restated its recommendation that everybody eat at least two fish servings a week.On the other hand,fish that live in contaminated waterways contain high levels of mercury,which can lead to cognitive problems in developing brains.That's why pregnant women and nursing mothers are advised to limit their consumption. 
As if that weren’t confusing enough,two new studies published last week in the New England Journal of Medicine investigated the possible effects of mercury on the heart,and they seem to have reached contradictory conclusions.One found no clear link between mercury levels and heart disease; the other found that men with high levels of mercury in their toenails were more likely to suffer a heart attack than those with low levels.What are we to make of this? The first thing to remember is that this is how science proceeds,by fits and starts and seemingly contradictory results that get resolved only by further study.The second is that not all fish are created equal. 
Compared with all the other things you might eat,fish are an excellent source of protein.They tend to eat algae as part of their natural life cycle,converting it into omega-3 fatty acids that can improve your cholesterol profile.But it's also true that our waterways have become increasingly contaminated with all sorts of pollutants,including mercury,and that these pollutants tend to accumulate at different levels in different species.The fish most at risk are predators high in the pelagic food chain,such as swordfish and sharks. 
It was to test the effects of mercury on the heart that the two new studies compared the mercury levels in clippings from toenails,where heavy metals tend to be deposited. In one study,researchers led by Dr.Eliseo Guallar at Johns Hopkins found that European and Israeli men with the highest mercury levels were nearly 2.2 times as likely to have a heart attack as those with the lowest levels.The other study,led by Dr.Walter Willett at the Harvard School of Public Health,looked at a selection of American men and found no connection between mercury exposure and risk of heart disease,although Willett told me a“weak association” cannot be ruled out. 
For most of us,eating two servings of fish a week should not pose any problems.Guallar,who hails from coastal Spain,continues to flavor his paella with salmon,which has negligible mercury levels.Willett eats swordfish only about twice a month—because of its expense,not any fear of mercury.Fish-oil supplements are high in omega-3 fatty acids and probably don’t contain as much mercury as whole fish.But they don’t taste nearly as good. 
注(1):本文选自Time; 
注(2):本文习题命题模仿对象为2005真题Text 1。 
1.In the opening paragraph,the author introduces his topic by ______. 
A) making a comparison 
B) justifying an assumption 
C) posing a contrast 
D) explaining a phenomenon 
2.The phrase“by fits and starts”(Line 6,Paragraph 2)most probably means ______. 
A) something happens smoothly 
B) something keeps starting and then stops again 
C) something deserves a lot of effort 
D) something is troublesome 
3.Clippings from toenails were chosen for the research most probably because ______. 
A) they are more likely to contain mercury 
B) they influence a person's heart 
C) they can be easily obtained 
D) they are connected with the heart 
4.The views of Dr.Eliseo Guallar and Dr.Walter Willett are ______. 
A) identical 
B) similar 
C) opposite 
D) complementary 
5.What can we infer from the last paragraph? 
A) Fish is no threat to humans. 
B) Do not be frightened by some fish. 
C) Eat fish-oil supplements instead of fish. 
D) Taste is more important than the safety of the food. 

如果吃鱼对人体健康方面有所影响的报道令你感到困惑的话,那么有你这种感觉的并不单单是你一个人。一方面,美国心脏学会两周前再次建议大家每人每周至少吃两次鱼,他们是这样提醒我们的:鱼肉中所含的不饱和脂肪酸可以降低心脏病的发病率。另一方面,生长于污染水域的鱼体内存有高含量的汞,这可能对发育中的大脑造成认知方面的不良影响。这就是为什么要建议孕妇和哺乳期妇女减少鱼类摄入的原因。 
这好像还不足以使你感到困惑不解。上周刊载于《新英格兰医学杂志》上的两项新课题,就汞对心脏可能造成的影响进行了调查研究,两项研究却得出了似乎相互矛盾的结论:一项研究发现汞含量和心脏病之间没有必然联系;另一项研究发现脚趾甲中汞含量高的人与汞含量低的人相比,更容易患心脏病。我们该如何理解?首先要牢记这就是科学的进程,那些时进时退并且看起来相互矛盾的结论只能通过进一步的研究才能得以解决;其次,并不是所有的鱼类天生都一样的。 
与其他可食用物相比,鱼类是蛋白质的最佳来源。它们把食用海藻作为自然界生命循环的一部分,并将其转化为能促进胆固醇代谢的不饱和脂肪酸。但是我们越来越多的水源被各种污染物(其中包括汞)所污染也是事实,这些污染物在不同的生物体内以不同程度的含量积聚下来。最危险的鱼是处于海洋上层食物链中的食肉鱼,比如旗鱼和鲨鱼。 
脚趾甲是重金属易于沉积的地方。这两个新课题通过对比脚趾甲中汞的含量检测汞对心脏的影响。其中一个课题的研究员由约翰霍普金斯大学的埃利塞奥·瓜利亚尔博士领导,他们发现在欧洲人和以色列人当中,体内汞含量最高的人犯心脏病的几率几乎为汞含量最低的人的2.2倍。另一项课题由哈佛公共卫生学院的沃尔特·威利特博士领导。通过对那些选出来的美国男性公民的研究,他们并未发现人体接触汞元素和心脏病发病之间有什么关系,虽然威利特说不能完全排除其中会有某种“微弱的联系”。 
对于我们大多数人来说,一周吃两份鱼类食品不会产生任何问题。鲑鱼中汞的含量可以忽略不计。来自西班牙海岸的瓜利亚尔继续在他吃的肉菜饭里加鲑鱼调味。威利特大约每月只吃两回旗鱼——这是因为旗鱼太贵,而不是因为担心汞含量的问题。鱼油补充品富含不饱和脂肪酸,其中所含的汞元素可能也没有整条鱼那么多,但它们的口感实在太差。 
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