38.Olestra is different from ordinary fats in that_______.

　　A) it passes through the intestines without being absorbed

　　B) it facilitates the absorption of vitamins by the body

　　C) it helps reduce the incidence of heart disease

　　D) it prevents excessive intake of vitamins

　　39.What is a possible negative effect of olesira according to some critics?

　　A) It may impair the digestive system.

　　B) It may affect the overall fat intake.

　　C) It may increase the risk of cancer.

　　D) It may spoil the consumers' appetite.

　　40.Why are nutritionists concerned about adding vitamins to olesira?

　　A) It may lead to the over-consumption of vitamins.

　　B) People may be induced to eat more than is necessary.

　　C) The function of the intestines may be weakened. 跨段

　　D) It may trigger a new wave of fake food production.

　　Imagine eating everything delicious you want - with none of the fat. That would be great, wouldn't it?

　　New "fake fat" products appeared on store shelves in the United States recently, but not everyone is happy about it. Makers of the products, which contain a compound called olestra, say food manufacturers can now eliminate fat from certain foods. Critics, however, say the new compound can rob the body of essential vitamins and nutrients (營(yíng)養(yǎng)物) and can also cause unpleasant side effects in some people. So it's up to decide whether the new fat-free products taste good enough to keep eating.

　　注：eliminate消除

　　Chemists discovered olestra in the late 1960s, when they were searching for a fat that could be digested by infants more easily. Instead of finding the desired fat, the researchers created a fat that can't be digested at all.

　　Normally, special chemicals in the intestines (腸)"grab" molecules of regular fat and break them down so they can be used by the body. A molecule of regular fat is made up of three molecule of substances called fatty acids.

　　The fatty acids are absorbed by the intestines and bring with them the essential vitamins A, D, E, and K. When fat molecules are present in the intestines with any of those vitamins, the vitamins attach to the molecules and are carried into the bloodstream.

　　Olestra, which is made from six to eight molecules of fatty acids, is too large for the intestines to absorb. It just slides through the intestines without being broken down. Manufacturers say it's that ability to slide unchanged through the intestines that makes olestra so valuable as a fat substitute. It provides consumers with the taste of regular fat without any bad effects on the body. But critics say olestra can prevent vitamins A, D, E, and K from being absorbed. It can also prevent the absorption of carotenoids (類胡蘿卜素), compounds that may reduce the risk of cancer, heart disease, etc.

　　Manufacturers are adding vitamins A, D, E, and K as well as carotenoids to their products now. Even so, some nutritionists are still concerned that people might eat unlimited amounts of food made with the fat substitute without worrying about how many calories they are consuming.

　　原文重現(xiàn)、盡量少讀、怎樣找到but, only 細(xì)節(jié)題(一般讀兩三行)

　　21.What brought about the decline in the demand for American farm products?

　　A) The impact of the Great Depression.

　　B) The shrinking of overseas markets.

　　C) The destruction caused by the First World War.

　　D) The increased exports of European countries.

　　22.The chief concern of the American government in the area of agriculture in the 1920s was ______.

　　A) to increase farm production

　　B) to establish agricultural laws

　　C) to prevent farmers from going bankrupt

　　D) to promote the mechanization of agriculture

　　23.The Agricultural Adjustment Act encouraged American farmers to ______.

　　A) reduce their scale of production

　　B) make full use of their land

　　C) adjust the prices of their farm products

　　D) be self-sufficient in agricultural production

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