问题 填空题

一只蚂蚁在三边边长分别为3,4,5的三角形的边上爬行,某时刻该蚂蚁距离三角形的三个顶点的距离均超过1的概率为______.

答案

如下图所示,当蚂蚁位于图中红色线段上时,距离三角形的三个顶点的距离均超过1,

由已知易得:红色线段的长度和为:6

三角形的周长为:12

故P=

6
12
=
1
2

故答案为:

1
2

填空题

阅读短文,根据短文内容及首字母提示,在空白处填入一个适当的单词。

       Ron, the teacher at the skydiving (跳伞运动) school, was surprised when the gray-haired man said that his

name was Walter and asked if he could take skydiving lessons. Ron asked him how old he was and he

(1) r           that he was 60. Ron explained to Walter that (2) a            over 50 had to be checked by a doctor

before he could learn to jump from a plane. "I'm sorry, but I can't let you start learning (3) w            a letter

from your doctor."

       Walter smiled. "Here is a letter from my doctor. He asked me to take (4) l             of tests and he says that

I'm fine."

       So Walter was able to join the skydiving school. He came to all the lessons and worked very (5) h          .

Soon it was the time for him to make his (6) f             jump. Ron asked him if he was feeling OK. Walter

answered that he had never felt better. However, he added that there was something he should have told Ron

(7) e           . Ron asked what it was and Walter smiled. Then just before he jumped, he told Ron that he wasn't

60. Ron asked how old Walter (8) r            was and Walter told him he was 75!

       Walter has a lot of (9) h           . He enjoys riding fast motorbikes and (10) c            mountains. Last year

he was saved by a police helicopter (直升飞机) in Wales.

       His daughter Betty worries about him. "I think he should stop all these activities. But my mother says that

as long as he's happy, it's OK."

选择题