阅读理解。
Jack is a twenty-year-old yo
ung man. Two years ago, when he finished middle school, he found work
in a shop. Usually he works until ten o'clock in the evening. He is very tired when he gets home. After a
quick supper he goes to bed and soon falls asleep. His grandma who lives downstairs is pleased
(高兴的) with him.
One day, on his way home, he met his friend Mary. They were both happy. He asked the girl to his
house, and she agreed happily. He bought some fruit and drinks for her. And they talked about their
school, teachers, classmates and their future. They talked for a long time.
"Have a look at your watch, please," said the girl. "What time is it now?"
"Sorry, something is wrong with my watch," said Jack. "Where's yours?"
"I left it at home."
Jack thought for a moment and found a way. He began to stamp his foot on the floor, "Bang! Bang!
Bang!"
The sound woke his grandma up. The old woman shouted downstairs, "It's twelve o'clock in the
night. Why are you still jumping upstairs?"
1. Jack was _____ when he finished middle school.
A. sixteen
B. eighteen
C. twenty
D. fifteen
2. The old woman is satisfied (满意的) with Jack because _____.
A. He's her grandson.
B. He's clever.
C. He can keep quiet.
D. He gets home on time.
3. From the story, we can know that Ma
ry is Jack's _____.
A. classmate
B. colleague (同事)
C. aunt
D. wife
4. The word "stamp" in the story means _____ in Chinese.
A. 盖印
B. 跺
C. 贴邮票
D. 承认
5. Jack stamped his foot on the floor in order to (为了) _____.
A. wake his grandma up
B. make his grandma angry
C. l
et his grandma tell him the time
D. let his grandma buy him a watch
的光滑斜面上，并被斜面上一个竖直的光滑挡板挡住，处于平衡状态。求斜面对球体的支持力和挡板对球体的支持力？
（g取10m/s2，sin37°=0.6、cos37°=0.8）。
