Passage Two
From the beginning of human history, [31]people have used oils from seeds and nuts. [29]Most of the time these oils are used as food, especially in cooking. But sometimes they have other uses. [29]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. [30]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.

答案解析：
Questions 29 to 31 are based on the passage you have just heard.
29. What use of oil is NOT mentioned in the passage?
[C]解析：短文第2句開始談植物油的用處，提到了cooking，paint和cleaning products，只有C項(xiàng)未提及，因而它就是答案。
30. How much oil does soybean contain?
[D]解析：短文提到，大豆的含油量為20%，故選D。百分比作選項(xiàng)，難點(diǎn)不在猜測問題是什么類型，而在于對文中出現(xiàn)的每個百分比（50%和20%）做出準(zhǔn)確的筆記。在聽到問題后才能根據(jù)筆記作答。
31. Which of the following is the best title for the passage?
[A]解析：短文第1句指出，人類使用植物（種子）油有著漫長的歷史。然后談到植物油的用途，主要的植物油來源以及提取植物油，因此，本文的主題是A。從選項(xiàng)的高度概括性來看，本題當(dāng)問文章的主旨大意。核心詞是oil，然后每個選項(xiàng)都給出了另一個關(guān)鍵詞：seeds，market，food，soybean。本文多處提到oil和seeds，因此不難選出答案。其他幾項(xiàng)的關(guān)鍵詞只是文章中的局部內(nèi)容，不能充當(dāng)主題。