问题 应用设计题

请将左图中的“光控开关”、“声控开关”、灯泡用笔画线代替导线正确连入电路,设计出只有在光线很暗且有声音时灯才亮的楼道灯自动控制电路,同时安装一个不受开关控制的三孔插座(光线很暗时“光控开关”闭合,有声音时“声控开关”闭合);请在右图中根据小磁针静止时N极的指向,标出电源的正极,并用箭头标出磁感线的方向。

答案

见下图:

题目分析:两个开关同时控制一盏灯,只有两个开关全部闭合时灯才发光,所以两个开关是串联的,再有,在家庭电路中,开关应接在灯与火线之间才安全,因为火线和大地之间有220V的电压,这样接能保证断开开关时,用电器就与火线断开连接,不会发生触电事故;

三孔插座的接法是上地、左零、右火;

根据小磁针的指向可知通电螺线管左端是S极,用安培定则可判断电源左端是正极,如下图所示:

阅读理解

Mark was walking home from school one day when he noticed that the boy ahead of him had tripped and dropped all the books he was carrying, along with two sweaters, a baseball bat, a glove and a small tape recorder. Mark knelt down and helped the boy pick up the scattered articles. Since they were going the same way, he helped to carry part of the burden. As they walked, Mark discovered the boy’s name was Bill, that he loved video games, baseball and history that he was having a lot of trouble with his other subjects and that he had just broken up with his girlfriend.

Mark went home after leaving Bill at his house. They continued to see each other around school, had lunch together once or twice, and then both graduated from junior high school. They ended up in the same high school, where they had brief contacts over the years. Finally the long-awaited senior year came. Three weeks before graduation, Bill asked Mark if they could talk.

Bill reminded him of the day years ago when they had first met. “Do you ever wonder why I was carrying so many things home that day?” asked Bill. “You see, I cleaned out my locker because I didn’t want to leave a mess for anyone else. I had stored away some of my mother’s sleeping pills and I was going home to commit suicide(自杀). But after we spent some time together talking and laughing, I realized that if I had killed myself, I would have missed that time and so many others that might follow. So you see, Mark, when you picked up my books that day, you did a lot more. You saved my life.”

小题1:What happened to Bill on his way home from school?

A.Bill almost killed himself.

B.Bill was caught on something and almost fell down.

C.Bill was sleepy from the sleeping pills.

D.Bill noticed Mark following him home.小题2:After Bill got home,           .

A.he missed his friend Mark very much

B.he decided to break up with his girlfriend

C.he intended to kill himself immediately

D.he thought of the friendliness of Mark小题3:Mark saved Bill from committing suicide by          .

A.helping Bill pick up the fallen books on the ground

B.saying something comfortable and friendly to Bill

C.persuading Bill not to leave a mess for other people

D.being friendly to Bill in trouble小题4:Bill cleared his locker in order to           .

A.store away some of his mother’s sleeping pills

B.prepare for the next school year of high school

C.leave the world without troubling others

D.help his mother do some housework the last time

判断题