问题 问答题 论述题

工业上常用的热电阻有哪两种?它们的分度号是什么?常用的测量范围是多少?其0℃的标称电阻值R(0℃)是多少?其准确度等级分为哪两种?

答案

参考答案:

工业上常用的热电阻有两种,为铜热电阻和铂热电阻。铜热电阻的测温范围为-50~150℃,铂热电阻的测温范围为-200~850℃。铜热电阻的分度号为Cu50和Cu100,其0℃的标称电阻值R(0℃)分别为50Ω和100Ω。铂热电阻的分度号为Pt100Pt10,其0℃的标称电阻值R(0℃)分别为100Ω和10Ω。其准确度等级分为A级和B级两种。

阅读理解

阅读理解

     Tom arrived at the bus station quite early for a Paris bus. The bus for Paris would not leave until five

to twelve. He saw a lot of people waiting in the station. Some were standing in line, and others were

walking around. There was a group of schoolgirls. Their teacher was trying to keep them in line. Tom

looked around, but there was no place for him to sit.

     He walked into the station cafe. He looked up at the clock there. It was only twenty to twelve. He

found a seat and sat down before a large mirror on the wall. Just then, Mike, one of Tom's workmates

came in and sat with Tom.

     "What time is your bus?" asked Mike.

     "There's plenty of time yet," answered Tom.

     "Well, I'll get you some more tea then," said Mike.

     They talked while drinking. Then Tom looked at the clock again. "Oh! It's going backward!" he cried. "A few minutes ago it was twenty to twelve and now it's half past eleven."

     "You're looking at the clock in the mirror." said Mike. Tom was so sad. The next bus was not to leave

for another hour. Since then Tom has never liked mirrors. 

1. Tom went into the station cafe because_____.

A. Mike asked him to have a cup of tea

B. it was quite early and he could find a seat there

C. he didn't like to stay with the schoolgirls

D. he wanted to have a drink with his workmate there

2. What time was it in fact when Tom looked at the clock in the mirror?

A. Half past twelve.

B. Twenty to twelve.

C. Half past eleven.

D. Half past one.

3. From the story we know that when we look at a clock in a mirror, we will find _____.

A. the time is right

B. it's going slower

C. it's going backward

D. it's going faster

4. Which of the following is true?

A. Tom arrived in Paris on time.

B. The next bus would leave in half an hour.

C. After that Tom didn't like clocks any longer.

D. Tom looked at the clock in the mirror only once

单项选择题