问题 问答题

一根黄铜圆棒,直径d1为25mm,长度L1为400mm,现将外圆车去10mm后,温度从室温15℃升到55℃,黄铜的线胀系数为17.8×10-6l/℃,求此时铜棒的长度。

答案

参考答案:

由公式

得:L2=L1t△tL1………①

已知:αt=17.8×10-6l/℃

△t=t2-t1=55-15=40℃

L1=400(mm)

代入①式得:

L2=400+17.8×10-6×40×400

≈400.285(mm)

此时黄铜棒长约为400.285mm。

阅读理解

阅读理解。

     Some people think only school children do not agree with their parents. However, it is not true.

     Communication is a problem for parents and children of all ages. If it's hard for you to communicate with

your parents, don't worry about it. Here is some advice for you to bridge the generation gap (代沟).

     ● Don't argue (争辩) with your parents. Don't get to your parents when you are angry. Your parents

probably won't consider your ideas if you are shouting at them. And you can't express yourself well if you are

angry. Go someplace to cool off. Make sure you understand why you are unhappy. Then think about what you

want to say to your parents. If you don't think you can speak to them at the moment, try writing a letter.

     ● Try to reach a compromise (和解). Perhaps you and your parents disagree on something. You can keep

your disagreement and try your best to accept each other. Of course, your parents might refuse to compromise

on something. In these situations, it is especially important to show love and respect to them. Showing respect

will keep your relationship strong.

     ● Talk about your values. The values of your parents are probably different from those of your own. Tell

your parents what you care about, and why. Understanding your values might help them see your purposes in

life. 

     A good relationship with your parents can make you a better and happier person. It is worth having a try!

1. Your parents probably won't consider your ideas if you _____.

A. don't get to them often

B. write a letter to them

C. don't speak to them politely

D. express yourself well

2. If there's really a generation gap between you and your parents, you'd better _____.

A. have a talk with them often

B. keep away from them

C. agree with them all the time

D. know about their values

3. From the passage we learn that _____.

A. parents and children should not have a generation gap

B. there are some good ways to bridge the generation gap

C. parents should show love and respect to their children

D. there are so many serious problems in families today

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