问题 填空题

直角三角形的两条直角边分别长5和12,三角形内一点到三边的距离都为d,则d=______.

答案

由题意知:AC=12,BC=5,

OE⊥BC,OD⊥AC,OF⊥AB

则根据勾股定理AB=

AC2+BC2
=13,

直角△ABC面积为

1
2
×5×12=30,

直角△ABC的面积又等于△ACO、△ABO、△BCO的面积和,

1
2
AC×OD+
1
2
BC×OE+
1
2
AB×OF=30,

∵OD=OE=OF,且AC+BC+AB=5+12+13=30,

∴OD=OE=OF=2,

故答案为 2.

阅读理解

The computer is important and can help us do a lot of things. Lots of children spend too much time on the computer. It’s bad for their study. Here is some advice(建议) for the parents.

◆Move the computer out of the child’s bedroom. It is good for children to reduce (减少) the time to use the computer.

Set a password for the computer. If your child wants to use it, he/she should get your permission (允许).

◆If your child uses the Internet for studying. He / She doesn’t use it to play games, praise (表扬) him/her for that.

◆When your child wants to use the computer to play games, you can take her/him to the library, get her/him together with friends to play sport.

小题1:The first advice (建议) is “________”.

A.Set a password for the computer

B.Set a time-limit for playing on the computer

C.Spend much time playing sport with the child

D.Move the computer out of the child’s bedroom小题2:The underlined phrase “Set a password” means ________ in Chinese.

A.设置桌面

B.设置密码

C.修改程序

D.更换电脑小题3:If your child uses the computer for studying, you can say “________” to him/her.

A.Sorry

B.Happy birthday

C.Good

D.No小题4:This passage is writing to ________.     

A.students

B.teachers

C.parents

D.workers小题5:What can the parents do when the child wants to play computer games?

A.They can take her/ him to the library.

B.They can let her/ him play computer games.

C.They can take her/ him to school.

D.They can praise him/her.

单项选择题