问题 选择题

如图所示的电路中,电源电压保持不变。闭合电键S,灯不亮,再闭合电键S1,发现两电表示数均不发生变化,如果电路中只有灯或电阻出现故障,则下列判断中正确的是

A.一定灯短路

B.一定电阻短路

C.可能电阻断路

D.可能灯断路

答案

答案:C

题目分析:观察图5,若灯短路,闭合开关S后再闭合开关S1,两表示数都没有变化;若电阻短路,闭合开关S后再闭合开关S1,电压表示数不变(为0),电流表示数增大(可能损坏);若电阻断路,闭合开关S后再闭合开关S1,两表示数都没有变化;若灯泡断路,闭合开关S后再闭合开关S1,两表示数都有变化;所以灯短路或电阻断路都会引起两表示数没有变化,对照各选项,C符合题意,选填C。

阅读理解

阅读理解。

     I sat at my seat waiting for the school paper to be passed around. I waited anxiously, knowing that

once I received it I would know how good a writer I really am.

     When the paper arrived at my classroom, I nearly knocked down five of my classmates to get to the

first paper. With a school paper in my hands, I returned to my seat. About a month earlier, I had handed

in one of, what I believed to be, my best stories. I named it Symbol of Success. The head of the English

Department at my school, Professor Cullen had said that she would include some reviews of students'

stories in the latest school paper. Professor Cullen was known for her rough criticism. Impressing her

was very hard but I wanted to be the first to do so.

     I sat at the edge of my seat as I read through the other story reviews. There wasn't one story that got

more than three stars .I became calm and wasn't anxious to know my review. It was long after that I

heard someone shout out "Five stars?! Seriously !" from behind me. I turned around and saw the

shocked expression of Gene's face, "Peter, your story got five stars!" I couldn't believe what I was

hearing. I turned my attention back to my story and saw the five stars at the end of the review that I had

not read yet. I looked through the review written by Professor Cullen. She wrote that I had a gift for

story writing.

     I was proud that I achieved what I thought was impossible .For so long I believed I wasn't as good as

I thought I was and that my talent was not enough to cover up my lack of wring skills .But this review

proved that I was truly a good writer and that there was a future ahead of me in the field of fiction writing. The review and the five stars meant the world of me. Those five stars became the symbol of my success.

1. How did the writer get the school paper?

A. His teacher gave it to him first

B. The publisher sent it to him first

C. His friend helped him get the first one.

D. He rushed ahead to get the first one by himself.

2. What can we learn about Professor Cullen? 

A. She was very gentle to everyone

B. She seldom praised her students.  

C. She was very cold to her students.  

D. She was respected by her students.

3. We can learn from this text that Peter_______.

A. had thought his story was better than those of others

B. was always anxious to know the review about him

C. didn't know he got five stars until others told him

D. looked through a few stories that had got four stars

4. What did Professor Cullen think of Peter's story?

A. She thought highly of it  

B. She thought it was just so-so  

C. She thought it was extremely bad 

D. She doubted if it was written by him.

5. Why did the review and the five stars mean the world to Peter?

A. Because they helped him learn writing skills

B. Because they made him happy for some time

C. Because they helped him enter a key university

D. Because they made him see his writing talents.

判断题