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问题 填空题

线段2cm、8cm的比例中项为______cm．

答案

根据比例中项的概念结合比例的基本性质，

得：比例中项的平方等于两条线段的乘积．

设它们的比例中项是x，则x2=2×8，x=±4（线段是正数，负值舍去），故填4．

填空题

根据短文内容及首字母提示，填写所缺单词。

       Children's education is changing very fast today. In the past, teachers made children s  1   quietly for

hours. They made them r  2   all kinds of things. The children had to go on r  3   things again and again

until they knew them "by heart". Today, many teachers wonder if it is p  4   to make children learn at all.

They say you can o  5   help them learn. They say you must let children learn and discover things for t  6  . But for some of the children, school is a kind of p  7   they can't escape(逃亡) from. They are there only b  8   their parents make them go. They get out of the classroom as soon as the teachers let them leave.

Many of them want to find j  9   but the law(法律) will not let them work until they reach a certain(一定的) age. And so, they have to stay in school. O  10   they do not learn anything at all and hate every

moment.
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填空题
设a=2
1
5
，b=(
1
5
)2，c=log2
1
5
，则a、b、c的大小关系为______．
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