问题 填空题

将一支铅笔芯接在3V电源两端,测出通过铅笔芯的电流是0.15A;若将这支铅笔芯两端的电压增加到6V,则通过它的电流是______A。当电压变为零时,导体的电阻为        

答案

0.3;20Ω

题目分析:

因为电阻是本身的材料、粗细、长度决定的,与电压及电流无关,所以电压增加及变为零,电阻都不变仍为原来的大小。

点评:关键是明白电阻是本身的材料、粗细、长度决定的,与电压及电流无关。

阅读理解

The other day I heard a few local musicians talking, "I hate all the pianos in this town and I hate that rubbish they play on the radio. They cannot even understand rhythm (韵律).""Nobody wants to pay musicians anything. I’m sick of all the people who want you to play without paying you.” One younger musician said, "There are a couple of clubs who want me to play for a few nights a month, and I’m trying to find other places to play. I’m also planning to join in several summer festivals this year." I really liked what the younger musician said so I made friends with him.

Attitudes are important. Whether they’re positive or negative (消极的), they’re all rubbing off on you. If you’re around people who are always complaining(抱怨) or blaming (责备) others, it is possible that you will start doing the same as well. If you spend lots of time with people who don’t support your dreams, it is time to take a look at the people you call "friends".

There is an easy exercise you can try. Make a list of the people who you often stay with, and simply stop spending time with the negative people on your list. Set a new standard for yourself and don’t become friends with people who fall below that standard. The choice is always yours to make. Of course, this exercise is entirely different from making friends only for the good of oneself. We really should try to help and spend time with those who are working towards a goal or dream.

小题1:The musicians’ conversation at the beginning is to show that ______.

A.musicians’ living conditions are not good

B.people in that town have poor taste in music

C.different people have different attitudes

D.young people are more likely to succeed小题2: The underlined part "they’re rubbing off on you" in Paragraph 2 means ______.

A.they’ll push you ahead

B.they’ll have an influence on you

C.they’ll keep you from moving on

D.they’ll help you realize your dreams小题3:Why did the author want to make friends with the younger musician?

A.He is more active than the others.

B.He can earn more than the others.

C.He has more things to do than the others.

D.His attitude is more positive than the others.小题4:By doing the exercise mentioned in Paragraph 3, you can ______.

A.make the right kind of friends

B.improve your ability to make friends

C.develop a better relationship with your friends

D.make some new friends with the same interests as you小题5:We can get the following information from the passage EXCEPT ______.

A.the younger musician is a positive person and would be a good friend

B.one will start complaining if one spends too much time with negative people

C.the exercise can help you keep close to really helpful friends

D.one should avoid making friends with people who have lots of difficulties

单项选择题