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 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 (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.
简短回答题评分原则及标准
1. 评分原则
简答题要求考生在读懂文章的基础上，用正确简洁的语言回答问题。在评分时应同时考虑内容和语言。每题满分为2分，最低为0分。
2. 给分标准
2分--答出全部内容，语言正确;
1分--答出部分内容，语言正确;
0分--没有答对问题。
扣分标准
(1)语言有错误扣0.5分(不包括引起歧义的，可以辨识的拼写错误)，每题由于语言错误扣分不能超过0.5分;
(2)涉及无关内容者扣0.5分;其答案中有相互矛盾的内容，则内容矛盾的部分均不得分;
(3)整句原封不动照搬应扣分;照搬一句扣0.5分;照搬两句及两句以上者扣2分;
(4)考生所给答案超过10个单词扣0.5分。
Part IV Short Answer Questions (15 minutes)
Joe Templer should have known better: after all, he works for a large auto-insurance company. It won't hurt to leave the key in the truck this once, he thought, as he filled his gas tank at a self-service gas station. But moments latter as he was paying the money he saw the truck being driven away.
In 1987, 1.6 million motor vehicles were stolen in the United States-one every 20 seconds. If current trends continue, experts predict annual vehicle thefts could exceed two million by the end of the decade.
Vehicle theft is a common phenomenon, which has a direct impact on over four million victims a year. The cost is astonishing.
Many police officials blame professional thieves for the high volume of thefts. It is a major money-maker for organized crime. Typically, stolen cars are taken to pieces and the parts sold to individuals. But as many as 200.000 cars are smuggled out of the country every year. Most go to Latin America, the Middle East and Europe.
Only about 15 percent car thefts result in an arrest, because few police departments routinely conduct in-depth auto-investigations. When thieves are arrested, judges will often sentence them to probation (缓刑), not immediately put them in prison because the prisons are overcrowded with violent criminals.
One exception is a Michigan program that assigns 92 police officers to work full-time on the state's 65,000 car theft cases a year. Since 1986, when the effort began, the state's auto-theft rate has fallen from second in the nation to ninth.
How can you protect your car? If you live in a high-theft area or drive an expensive model, consider a security system. It may cost anywhere from $25 to $1,000. Some systems engage automatically - simply removing the key disables the fuel pump the fuel pump and the starter. When cars are equipped with such systems, thefts may drop by one-third. In some states, you may be able to sue a device that transmits radio signals, allowing stolen cars to be tracked by police.
Questions:
71. What is the passage mainly about?
________________________________________________________
72. What does the author think Joe Templer should be blamed for?
Leaving the key in the truck
73. How serious did the author predict the annual vehicle theft could in the United States in 1989?
________________________________________________________
74. What are the two ways thieves sell the stolen cars?
________________________________________________________
75. What type of security system can help the police track down a stolen car?
________________________________________________________
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