问题 问答题 简答题

什么是抗弯应力?

答案

参考答案:

作用在物体上的外力是通过物体纵向中心线平面的一对力矩,或在物体两搁放处(力学称搁置点)的中间部分,作用一个或几个垂直于纵向中心线的力,在上述两种情况下物体截面上的内力主要是弯矩,使物体的纵向中心缚从直弯曲成曲线之倾向,此时物体截面上沿弯矩方向所发生的应力,叫抗弯应力。

配伍题 B1型题
阅读理解

阅读理解。

     "It was all his own idea," says Pat Peters, the 38-year-old wife of Palo Alto (帕罗奥图市

,属美国加利福利亚州), California high school football coach Bob Peters, 39. Bob had just

drawn up a "motherhood contract" - a document stating that for 70 days this summer he would

take over the care and feeding of the couple's four children, plus all household chores. Although

he didn't even know how to make coffee when he signed, he was quite confident. (He though

t the experience would make a nice book.)

     After 40 of the 70 days, he was ready to give up. "I was beaten down, completely humbled,"

admits Peters. Three weeks later he spoke to the local press (also part of the bargain), stating,

"Not only is motherhood a difficult task, not only is it never-ending, it is an impossible job for

any normal human being."

     Bob and Pat were high school sweethearts. After they were married in 1960, she worked as

a secretary to help pat him through university. Since then Bob has been the football and wrestling

coach at Palo Alto's Cubberley High while Pat raised the kids.

     Then two years ago Pat went back to work as a secretary at Cubberley. "I had been around

children so much, "she sighs, "I couldn't talk to a grown-up." She continued to run the house-hold,

however  until Bob signed the contract, whereupon she decided to relax and enjoy it. Although

Peters had consulted (咨询) with his school's home economics teachers and the head of the

cafeteria (食堂), his meals were sometimes a disaster. "I tried to slip the butter I'd forgotten under

the eggs after they were frying," he says. For the last three weeks, the family ate out a lot sometimes

having Macdonald's hamburgers for lunch and dinner.

     As for housekeeping, a home economics teacher had told Bob that a room always looks clean

if the bed is made. "I found an easier way I shut the doors," he says. Soon the kids were wearing

the same clothes for a week. I made them wear their shirts inside out, and when we went to pick

up Pat at work they turned them right side out so they would look clean."

    Now that Bob has publicly admitted he was wrong, he is routinely (日常地)sharing the child-raising

and household tasks with Pat. The tentative (暂定的) tide of his book about the summer is taken

from something he shouted at the kids one day.

1. The couple signed the contract because ______.

A. Pat complained a lot about her doing the housework all by herself

B. Bob loved taking care of children and wanted his wife to have a good rest

C. they agreed that husband and wife should share household tasks

D. Bob thought it easy to take care of the family and wanted the experience for a book

2. What can we learn about Pat Peters?

A. She was hard-working and selfless.B. She was pretty and kind-hearted.

C. She was tired of the child-raising and household tasks.

D. She did not love Bob any longer

3. Which of the following can best end the news story?

A. "My experience of being a mother."

B. "I'm proud of you all, my dear!"

C "Wait till your mother gets home!"    

D. "Motherhood: an impossible job for anyone."

4. Which of the following is true according to the passage?

A. Bob managed to keep the kids' clothes clean.

B. Bob tried to cook good meals for his children.

C. Bob frequently took the kids out to eat because he was too busy at work.

D. Bob taught the kids to make their beds every day.