搜题请搜索小程序“爱下问搜题”
问题 选择题

下列性质中，等腰三角形具有而直角三角形不一定具有的是…………（   ）

A．内角和等于180°

B．有一个角的平分线垂直于这个角的对边

C．有两个锐角的和等于90°

D．有两条边的平方和等于第三条边的平方

答案

答案：B

根据等腰三角形与直角三角形的性质作答．

解：A、对于任意一个三角形都有内角和等于180°，不符合题意；

B、等腰三角形顶角的平分线垂直于顶角的对边，而直角三角形（等腰直角三角形除外）没有任何一个角的平分线垂直于这个角的对边，符合题意；

C、只有直角三角形才有两个锐角的和等于90°，不符合题意；

D、只有直角三角形才有两条边的平方和等于第三条边的平方，不符合题意．

故选B．

点评：本题主要考查了三角形的性质，等腰三角形与直角三角形的性质的区别．

阅读理解
配对阅读 左栏是五位病人的健康问题，右栏是七位专科医生的简介。请根据五位病人的健康问题为他们选出最合适的专科医生诊病，并将答题卡上对应题目所选的选项涂黑。
小题1:Bob is often late for school because he always gets up late. This makes his teacher mad. He needs to buy something to wake him up in the morning.
小题2:Tim likes listening to music when he is free. And he has to send e-mails to his customers(顾客）every day. He wants to buy something that can help him.
小题3:Summer has come. Tony is fat and he can’t sleep well on such hot days. This troubles him a lot. He’d like to buy something to make him feel cool.
小题4:Alice often washes her hair late at night. It is often wet when she goes to bed. She is going to buy something that can dry her hair in a short time.
小题5:Susan is a housewife. She has to do the washing for her family every day. She gets tired of it. She is in need of a product to do it for her.
A．This electric product can make you cool during the hot days. It can help you change the temperature and control the humidity(湿度） of your room.
B．You can do many things with this product, such as sending e-mails, playing games, getting on line and so on. You can also listen to the music with it when you want to relax.
C．This electric product is useful to all of us. People often have one at home. It is often put up on the wall. If you want to know the time, just take a look at it.
D．This can help you wash your dirty clothes and dry them. What you need to do is to return it on and later hang the clothes on the line. With this electric product, life will be a lot easier for you.
E. Each family needs this product. You can use it to store meat, vegetables, fruits, drinks and medicine. It can keep them cool and fresh so that they will not go bad easily on hot days.
F. It is a very helpful product which tells you the time. It can wake you up with a piece of music any time you want, but you have to set the time first.
G. When you wash your hair, you need this product. It can make your wet hair dry in a minute. It can also be used for drying your wet clothes or some other wet things.
查看答案
单项选择题

留针可起到

A．行气作用

B．得气作用

C．催气作用

D．候气作用
查看答案