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问题 填空题

椭圆3x2+4y2=12的离心率为______．

答案

把椭圆方程化为标准方程得：

x2
4
+
y2
3
=1，得到a=2，b=
3
，

则c=

4-(
3
)2
=1，所以椭圆的离心率e=
c
a
=
1
2
．

故答案为：

1
2

选择题
如图所示的尺规作图是作（    ）

A．线段的垂直平分线
B．一个半径为定值的圆
C．一条直线的平行线
D．一个角等于已知角
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听力题

阅读短文，根据短文内容及首字母提示，填写所缺单词。(每空0．5分，共10空，计5分）

Bill Gates was born on October 28, 1955. He was n小题1:William Henry after his father and grandfather. He was a very clever boy. At school, his favourite s小题2:ere science and maths. When people asked him w  小题3:he wanted  to be  in  the  future, he always  said, "A scientist. "

When he was 13 years old, Bill started to play w 小题4:computers. At that time, a computer was a very large m小题5:Once he was interested in a very old computer. He and some of his friends spent lots of time d 小题6: unusual things with it. In the end, they worked out a software program(软件程序). Bill sold it for 4, 200 dollars when he was only 17.

In 1973, Bill went to Harvard University. There he developed the BASIC language for the first microcomputer (微机). But he didn't finish his studies in Harvard. In his t 小题7: year, he left Harvard to work for Microsoft (微软). He thought computer would be an i 小题8: tool (软件公司) in every office and in every home, s 小题9: he began developing software for personal computers. He made it much e 小题10: for people to use computers than before.
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