2020考研英語閱讀理解精讀100篇：Unit 91

Unit 91

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）：本文選自Time；

注（2）：本文習(xí)題命題模仿對象為2005真題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.

篇章剖析

本文采用提出問題—分析問題的模式，指出吃魚對心臟有好處，但是其中所含的汞卻對心臟有害，探討二者該如何取舍。第一段指出人們對吃魚對健康究竟有無影響、有何影響這一問題感到困惑；第二段以兩項新課題為例，進一步說明人們的這一困惑；第三段指出魚類自身所具有的優(yōu)點及其存在的一些潛在的危險；第四段詳細(xì)介紹這兩類新課題的研究發(fā)現(xiàn)；第五段間接指出我們該如何取舍。

詞匯注釋

omega-3 fatty acids （不飽和）脂肪酸

contaminate /k?n?t?m?ne?t/ v. 污染

by fits and starts間歇地，一陣一陣地

algae /??ld?i?/ n. 藻類，海藻

at risk 有危險

predator /?pred?t?(r)/ n. 掠奪者，食肉動物

pelagic /p??l?d??k/ adj. 浮游的，遠洋的

swordfish /?s??df??/ n. 旗魚

rule out 刪除，排除，取消

hail from 來自

paella /pɑ??el?/ n. （西班牙）肉菜飯

negligible /?negl?d??b(?)l/ adj. 可以忽略的，不予重視的

難句突破

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.

主體句式：It was... that...

結(jié)構(gòu)分析：本句是強調(diào)句型。判斷是否是強調(diào)句型的辦法是把“It was that”去掉，看是否仍是一個完整的句子。

句子譯文：腳趾甲是重金屬易于沉積的地方。這兩個新課題通過對比腳趾甲中汞的含量檢測汞對心臟的影響。

題目分析

1. C 論證方式題。在引入論題時，作者在第一段用了on one hand... on the other hand，意思是“一方面…另一方面”，就吃魚與否引出兩種完全不同的觀點，從而導(dǎo)致很多人就此問題感到困惑。

2. B 語義題。習(xí)語by fits and starts所在語境為“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.”從此句我們可看出科學(xué)的進程并不是一蹴而就的。此題我們可考慮使用排除法。

3. A 細(xì)節(jié)題。原文對應(yīng)信息在第四段：“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. ”本題的理解請見“難句突破”。

4. C 情感態(tài)度題。Dr. Eliseo Guallar和Dr. Walter Willett做的實驗相似，但是得出的結(jié)論卻完全不同。

5. B 推理題。原文對應(yīng)信息在末段“For most of us, eating two servings of fish a week should not pose any problems.”然后，作者又給出了兩個例子來進一步說明這一觀點。

參考譯文

如果吃魚對人體健康方面有所影響的報道令你感到困惑的話，那么有你這種感覺的并不單單是你一個人。一方面，美國心臟學(xué)會兩周前再次建議大家每人每周至少吃兩次魚，他們是這樣提醒我們的：魚肉中所含的不飽和脂肪酸可以降低心臟病的發(fā)病率。另一方面，生長于污染水域的魚體內(nèi)存有高含量的汞，這可能對發(fā)育中的大腦造成認(rèn)知方面的不良影響。這就是為什么要建議孕婦和哺乳期婦女減少魚類攝入的原因。

這好像還不足以使你感到困惑不解。上周刊載于《新英格蘭醫(yī)學(xué)雜志》上的兩項新課題，就汞對心臟可能造成的影響進行了調(diào)查研究，兩項研究卻得出了似乎相互矛盾的結(jié)論：一項研究發(fā)現(xiàn)汞含量和心臟病之間沒有必然聯(lián)系；另一項研究發(fā)現(xiàn)腳趾甲中汞含量高的人與汞含量低的人相比，更容易患心臟病。我們該如何理解？首先要牢記這就是科學(xué)的進程，那些時進時退并且看起來相互矛盾的結(jié)論只能通過進一步的研究才能得以解決；其次，并不是所有的魚類天生都一樣的。

與其他可食用物相比，魚類是蛋白質(zhì)的最佳來源。它們把食用海藻作為自然界生命循環(huán)的一部分，并將其轉(zhuǎn)化為能促進膽固醇代謝的不飽和脂肪酸。但是我們越來越多的水源被各種污染物（其中包括汞）所污染也是事實，這些污染物在不同的生物體內(nèi)以不同程度的含量積聚下來。最危險的魚是處于海洋上層食物鏈中的食肉魚，比如旗魚和鯊魚。

腳趾甲是重金屬易于沉積的地方。這兩個新課題通過對比腳趾甲中汞的含量檢測汞對心臟的影響。其中一個課題的研究員由約翰霍普金斯大學(xué)的埃利塞奧·瓜利亞爾博士領(lǐng)導(dǎo)，他們發(fā)現(xiàn)在歐洲人和以色列人當(dāng)中，體內(nèi)汞含量最高的人犯心臟病的幾率幾乎為汞含量最低的人的2.2倍。另一項課題由哈佛公共衛(wèi)生學(xué)院的沃爾特·威利特博士領(lǐng)導(dǎo)。通過對那些選出來的美國男性公民的研究，他們并未發(fā)現(xiàn)人體接觸汞元素和心臟病發(fā)病之間有什么關(guān)系，雖然威利特說不能完全排除其中會有某種“微弱的聯(lián)系”。

對于我們大多數(shù)人來說，一周吃兩份魚類食品不會產(chǎn)生任何問題。鮭魚中汞的含量可以忽略不計。來自西班牙海岸的瓜利亞爾繼續(xù)在他吃的肉菜飯里加鮭魚調(diào)味。威利特大約每月只吃兩回旗魚——這是因為旗魚太貴，而不是因為擔(dān)心汞含量的問題。魚油補充品富含不飽和脂肪酸，其中所含的汞元素可能也沒有整條魚那么多，但它們的口感實在太差。