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问题 选择题

I like hamburgers,         I don’t eat         .

A、but, they               B、and, them           C、but, them

答案

答案：C

题目分析：本题前句表示我喜欢汉堡，后句却表示我不吃他们，表示的是意思的转折，用but，又因“他们”做eat的宾语，故用宾格them，故本题选D。

点评：在英文中，我们应注意表示并列用and，表示转折用but，表示后果用or，表示结果用so，注意它们的使用和区别。

多项选择题

下列作业中，会产生生产性粉尘的有( )。

A．金属焊接加工

B．矿石或岩石的钻孔、爆破

C．有机物的不完全燃烧所产生的烟

D．危险化学品运输

E．金属研磨或切削
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单项选择题

(B)

You can tell the age of a tree by counting its ring. But these records of a tree’s life really say a lot more. Scientists are using tree ring to learn what’s been happening on the sun’s surface for the last ten thousand years. Each ring represents a year of growth. As the tree grows, it adds a layer to its trunk, taking up chemical elements from the air. By looking at elements in the rings from a certain years, scientists can tell what elements were in the air that year. Dr. Stevenson is analyzing one element, carbon-14, in ring from both living and dead tree. Some ring go back almost ten thousand year to the end of the Ice Age. When Stevenson followed the carbon-14 levels changed with the intensity of solar burning. You see, the sun has cycles. Sometimes it bums fiercely, and at other times it is relatively calm. During the sun’s violent periods, it throw off charged particles in fast moving streams called "solar winds". The particularly interfere with the formation of carbon-14 on earth. When there is more solar wind activity, less carbon-14 is produced. Ten thousand years of tree ring show that the carbon-14 level rises and falls about every 420 years. The scientists concluded that solar wind activity must follow the same cycle.

The purpose of the scientists in studying tree ring is to（）

A. examine the chemical elements in Ice Age

B. look into the pattern of solar wind activity

C. analyze the composition of different trees

D. find out the origin of carbon-14 on earth
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