阅读理解
Directions: Read the following passages and answer the questions. Choose the most appropriate answer for each question and circle the letter on the answer sheet. Remember to write the letter corresponding to the question number. 


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 (营养物) 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. 

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 (肠) “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 molecules 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 (类胡萝卜素), 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. 

单选题 We learn from the passage that olestra is a substance that ______.
【正确答案】 D
【答案解析】由第二段第二句“Makers of the products, which contain a compound called olestra, say food manufacturers can now eliminate fat from certain foods.”可知， 奥利斯特拉油现在可以消除某些食品中的脂肪。 故D最符合题意。 而批评家们提出该物质会夺走身体里的营养物， 且会造成副作用， 故A， B与此符合题意观点相悖。 C项未提及。
单选题 The result of the search for an easily digestible fat turned out to be______.
【正确答案】 D
【答案解析】由第三段最后一句“Instead of finding the desired fat, the researchers created a fat that can’t be digested at all.”可知， 研究人员非但没有找到理想的脂肪， 反而发现了一种人体根本无法消化的脂肪， 由此可见这是件出乎意料的事情。 故D为最佳答案。
单选题 Olestra is different from ordinary fats in that ______.
【正确答案】 A
【答案解析】由第六段第二句“It just slides through the intestines without being broken down.”可知， 奥利斯特拉油穿过肠道但是无法分解， 自然也不能像其他脂肪一样被吸收。 故A符合题意。
单选题 What is a possible negative effect of olestra according to some critics?
【正确答案】 C
【答案解析】本文倒数第二段最后一句话“It can also prevent the absorption of carotenoids （类胡萝卜素） , compounds that may reduce the risk of cancer,heart disease, etc.”指出批评家们认为这种脂肪阻止了人体对类胡萝卜素的吸收， 而类胡萝卜素能降低患癌症、 心脏病等疾病的风险。 因此， 它的负面影响最可能的是增加了患癌几率。 故C是正确答案。
单选题 Why are nutritionists concerned about adding vitamins to olestra?
【正确答案】 B
【答案解析】本文最后一句“concerned that people might eat unlimited amounts of food made with the fat substitute without worrying about how many calories they are consuming.”指出， 营养家们担心人们会食用过量脂肪替代品制成的食物， 而忽略了自己摄入了多少卡路里， 故B符合题意。 而选项A错在并非是食用过量的维他命， 而是由脂肪替代品制成的食物。