A、How to release oil from seeds. B、How to test the local market for oil. C、Food and oil. D、Soybean and oil. A短文第1句指出,人类使用植物(种子)油

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问题  
From the beginning of human history, people have used oils from seeds and nuts. Most of the time these oils are used as food, especially in cooking. But sometimes they have other uses. For example, oils are found in paint and in cleaning products, like soap. Oil is separated from seeds by using pressure. A machine called a press is often used. Sometimes it is surprising to learn how much oil the seeds contain. Sesame, cotton and sunflower seeds, for example, all contain at least 50% oil. Soybean is an important seed around the world, but it is only 20% oil. So chemicals are needed to release oil from soybeans. The first step in pressing the oil from seeds is to crush the seeds between two stones. A cloth container or bag is filled with the crushed seeds. Then the bag is hung up. Some of the oil will flow out of the bag and can be collected. But some oil will remain in the crushed seeds inside the bag. The easiest way to get the rest of the oil out is to place heavy rocks on the crushed material. Oil can also be collected with small, hand-operated machines. Small presses are important in areas where electricity or gasoline cannot be used. They are also a good way to test if a local market for oil exists.
19. What use of oil is NOT mentioned in the postage?
20. How much oil does soybean contain?
21. Which of the following is the best title for the passage?

选项 A、How to release oil from seeds.
B、How to test the local market for oil.
C、Food and oil.
D、Soybean and oil.

答案A

解析 短文第1句指出,人类使用植物(种子)油有着漫长的历史。然后谈到植物油的用途,主要的植物油来源以及如何提取植物油,因此,本文的主题是A。从选项的高度概括性来看,本题当问文章的主旨大意。核心词是oil,然后每个选项都给出了另一个关键词:seeds,market,food,soybean。本文多处提到oil和seeds,因此不难选出答案。其他几项的关键词只是文章中的局部内容,不能充当主题。
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