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问题 填空题
设集合M={y|y=|cos2x-sin2x|，x∈R}，N={x||x-
1
i
|＜
2
，x∈R，i为虚数单位}，则M∩N=______．
答案

M={y|y=|cos2x|}=[0，1]，

N={x||x+i|＜

2
}={x|
x2+ 1
＜
2
}={x|x2＜1}=（-1，1）

∴M∩N=[0，1）

故答案为：[0，1）

完形填空

SECTION C

Directions: Complete the following passage by filling in each blank with ONE word that best fits the context.

How much paper do you use every year? Probably you can’t answer this question quickly. In 1900,the world’s use of paper was about one kilogram  48  each person in a year. Now some countries use as  49 as 50 kilograms of paper for each person in a year. The amount of paper a country uses shows how far advanced the country is, some people say. It is difficult to say  50  this is true: different people mean different things  51  the word “advanced”. But countries like the United States, England and Sweden certainly use    52   paper than other countries.

Paper, like many other things that we use today, was first made in China. In Egypt and the West, paper was not very commonly used before   53  year 1400.The 54  wrote on papyrus; Europeans used parchment for many hundreds of years. Parchment was very strong ;   55  was made from the skin of a certain young animal. We have learnt some of the most important facts of European history from record that were kept on parchment.
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单项选择题

牵引变电所的自用电系统一般要求具有（）%的备用，通常都装设有两台自用电变压器。

A、50

B、80

C、90

D、100
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