问题 解答题

按要求作图并回答:

用刻度尺作线段AC (AC=5cm),以A为圆心,a为半径作圆,再以C为圆心,b为半径作圆 (其中a<5,b<5,且要求⊙A与⊙C交于B、D两点),连接BD.

(1)若能作出满足要求的两圆,则a、b应满足的条件是______.

(2)求证:AC⊥BD.

答案

(1)若能作出满足要求的两圆,则a、b应满足的条件是10>a+b>5;

2)连接AB、AD、BC、DC,

∵在△ADC和△ABC中,

AD=AB
AC=AC
DC=BC

∴△ABC≌△ADC(SSS ),

∴∠DAC=∠BAC,

∵AD=AB,

∴AC⊥BD.

阅读理解

阅读理解。

     I have an American friend. Her name is Lily. This is a picture of her new school. Look! There are six

 floors (层) in the teaching building. There are fifteen classrooms on every floor. In the school, there are

 3,200 students and 300 teachers. The teachers' offices are behind the classrooms. The dining hall is next

 to the teaching building. Lily often has lunch there. After lunch she often has a talk with her friends. In front

  of the dining hall is a library. It's a good place to read books.

     Lily gets to school at 7:40 a.m. The first class begins at 8:00 a.m. She has four lessons in the morning

  and two in the afternoon. There is a big gym behind the dining hall. After school, Lily likes going

 swimming there.

     The school is big and nice, and Lily likes it very much.

1. How many classrooms are there in the teaching building?

    A. Sixty.

    B. Seventy.

    C. Eighty.

    D. Ninety.

2. What does Lily like doing after school?

    A. Playing basketball.

    B. Going swimming.

    C. Talking with her friends.

    D. Reading books.

3. Where is the school library?

    A. It's behind the classrooms.

    B. It's next to the offices.

    C. It's in front of the dining hall.

    D. It's behind the dining hall.

4. What does the word "begin" mean in Chinese?

    A. 开始

    B. 结束

    C. 休息

    D. 计划

5. What's the best title (标题) of the passage?

    A. My American Friend

    B. Lily's Good Friends

    C. My Favourite School

    D. Lily's New School

判断题