问题 问答题 简答题

为什么要求压力表的实际工作压力要在最大量程的l/3至2/3之间?

答案

参考答案:

因为扁曲弹簧管对应的角度270°,正常工作的压力要使扁曲弹簧管旋转5至7°,此时压力表指针恰好在最大量程的1/3至2/3之间的范围内,所测量的压力准确。旋转超过了这个角度,指针超过了这个范围,则为超压工作,读数就有较大误差。所以在实际工作中要求压力要在压力表最大量程的1/3至2/3之间。

单项选择题 A1型题
阅读理解

Everyone knows about straight—A students. We see them frequently in TV situation comedies and in movies like Revenge of the Nerds(《菜鸟大反攻》),a comedy film satirizing(讽刺)social life in college. They get high grades,all right,but only by becoming dull laborers,their noses always stuck in a book. They are not good at social communication and look clumsy while doing sports.

How,then, do we account for Domenica Roman or Paul Melendres?

Roman is on the tennis team at Fairmont Senior High School. She also sings in the school singing group, serves on the students’ union and is a member of the mathematics society. For two years she has kept up A’s in every subject. Melendres, a freshman at the University of New Mexico,was student-body president at Valley High School in Albuquerque. He played soccer and basketball well, exhibited at the science fair,and meanwhile worked as a reporter on a local television station. Being a speech giver at the graduation ceremony,he achieved straight A’s in his regular classes,plus rewarding points for A’s in two college-level course.

How do super—achievers like Roman and Melendres do it? Brains aren’t the only answer “Top grades don’t always go to the brightest students,” declares Herbert Walberg, a professor of education at the University of Illinois at Chicago, who has conducted major studies on super—achieving students “Knowing how to make the most of your innate(天生的)abilities counts far more. Much more.”

In fact,Walberg says,students with high IQ sometimes don’t do as well as classmates with lower IQ. For them,learning comes too easily and they never find out how to get down.

Hard work isn’t the whole story, either.“it’s not how long you sit there with the books open.”said one of the many—A students we interviewed. “It’s what you do while you’re sitting.” Indeed,some of these students actually put in fewer hours of homework time than their lower-scoring classmates. The kids at the top of the class get there by mastering a few basic techniques that others can readily learn.

小题1:What can we conclude from the first paragraph?

A.Most TV programs and films are about straight-A students

B.People have unfavorable impression on straight—A students

C.Everyone knows about straight-A students from TV or films

D.Straight-A students are well admired by people in the society小题2:What will be talked about after the last paragraph?

A.The interviews with more students

B.The role IQ plays in learning well

C.The techniques to be better learners

D.The achievements top students make小题3:What can we infer from the passage?

A.IQ is more important than hard work in study

B.The brightest students can never get low glades

C.Top students certainly achieve all-around developments

D.Students with average IQ can become super-achievers