Passage10肺癌
Among all the malignancies,lung cancer is the biggest killer;more than 100,000Americans die of the disease,giving up smoking is one of obvious ways to reduce the risk,but another answer may lie in the kitchen.According to a new report,even heavy smokers may be protected from developing lung cancer by eating a daily portion of carrots,spinach or any other vegetable or fruit containing a form of vitamin A called carotene.
The finding,published in The Lancet,is part of a long-range investigation of diet and disease.Since1957,some American researchers have monitored the dietary habits and medical histories of2,000middle-aged men employed by the Western Electric Co.in Chicago.Led by Dr.Richard Shekelle of St.Luke’s Medical Center,and the researchers recently began to sort out the links between the subjects’dietary patterns and cancer.Other studies of animals and humans have suggested that vitamin A offers some protection against lung cancer.The correlation seemed logical,explains Shekelle,since vitamin A is essential for the growth of the epithelial(上皮的)tissue that lines the airways of the lungs.
But the earlier research did not distinguish between the two different forms of the vitamin.“Preformed”vitamin A,known as retinol,is found mainly in liver and dairy products like milk,cheese,butter and eggs.But vitamin A is also made in the body from carotene,which is abundant in a variety of vegetables and fruits, including carrots,spinach,squash,tomatoes,sweet potatoes and apples.
In the study,Shekelle and his colleagues found little correlation between the incidence of lung cancer and the consumption of foods containing preformed vitamin A.But when they examined the data on carotene intake,they discovered a significant relationship.Among the488men who had the lowest level of carotene consumption,there were14cases of lung cancer;in a group of the same size that ate the most carotene,only two cases developed.The apparent protective effect of carotene held up even for long-time smokers—but to a lesser degree.
Further studies will be necessary before the link between lung cancer and carotene can be firmly established.In the meantime,researchers warn against taking large numbers of vitamin A pills,because the tablets contain a form of the chemical that can be extremely toxic in high doses.Instead,they advise a well-balanced diet that includes goods rich in carotene.For a smoker,a half-cup of carrots every day might possibly make the difference between life and death.
1.The word“malignancy”(line1,Para.1)most probably refers to______.
A.cancer
B.sickness
C.vitamins
D.disease
2.Preformed vitamin A is NOT found in______.
k
B.eggs
C.apples
D.cheese
3.Carotene is present in all of the following EXCEPT______.
A.tomatoes
B.carrots
C.squash
D.butter
4.Among the groups studied,who had the most cases of lung cancer?
A.Those with the lowest level of carotene intake
B.Those with the highest level of carotene intake
C.Those who ate only foods containing carotene
D.Those with the lowest intake of carrots
5.What is needed to establish firmly the link between carotene and lung cancer?
A.Further study.
B.More money.
C.More cases of lung cancer
D.More people willing to eat carrots.
【答案与解析】
1.A原文中认为：lung cancer是所有恶性肿瘤中最大的杀手，由此可以推断应该是A
（cancer），癌症就是一种肿瘤。

2.C维A醛能在肝制品和奶制品中找到，可以根据这个来推断C（苹果）为正确答案。

3.D这道题的做法应该与72题的做法相同——排除法。

胡萝卜素一般都在蔬菜和水果中
可以找到，所有选项都是水果或蔬菜除了D（奶油）外，故D为正确答案。

4.A倒数第二段中说胡萝卜素摄入量最低的人群中患肺癌的最多，摄入胡萝卜素最多的人
群中患肺癌的人最少（2个）。

其余选项与原文相反或未提及。

5.A最后一段第一句即提供了很明确的答案：further study。

故A为正确答案。