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问题 选择题

下列对于我党历史上几次会议的中心内容的表述错误的是

A．“二大”：制定民主革命纲领

B．遵义会议：纠正“左倾”错误路线

C．“八大”：确定人民公社运动的方针

D．十一届三中全会：确定改革开放的战略

答案

答案：C

单项选择题

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.

When the sun burn fiercely, () carbon-14 is produced.

A. less

B. more

C. no

D. much
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单项选择题

观念之间的关系有（）类

A、一

B、二

C、三

D、四
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