问题 选择题

在如图所示的电路中,开关S闭合后,由于电阻元件发生短路或断路故障,电压表和电流表的读数都增大,则可能出现了下列哪种故障:(    )

A.R1短路

B.R2短路

C.R3短路

D.R1断路

答案

答案:A

题目分析:若各原件没有故障,电路正常,则电流表测量流过R1的支路电流,电压表测量R3两端的电压;若R1短路,则R2被短路,外电路只有电阻R3接在电源两端,电流表测量干路电流,电压表测量路端电压,两表示数均增大,故A正确.若R2短路,则R1被短路,电流表示数为零,显然不符合题意,故B错误.若R3短路,则电压表示数为零,不符合题意;故C错误.若R1断路,则电流表示数为零,也不符合题意,故D错误.故选:A.

单项选择题

Honesty comes in many forms. First there’s self honesty. Is what people see the real article or do you appear through smoke and mirrors I find that if I try to be something I’m not, I feel unsure of myself and take out a part from my PBA (personal bank account). I love how singer Judy Garland put it, "Always be a first class version of yourself, instead of a second class version of somebody else. "
Then there’s honesty in our actions. Are you honest at school, with your parents, and with your boss If you’ve ever been dishonest, I think we all have, try being honest, and notice how whole it makes you feel. Remember, you can’t do wrong and feel right. This story by Jeff is agood example of that:
In my second year of study, there were three kids in my math class who didn’t do well. I was really good at it. I would charge them three dollars for each test that I helped them pass. I’d write on a little piece of paper all the right answers, and hand them off.
At first I felt like I was making money, kind of a nice job. I wasn’t thinking about how it could hurt all of us. After a while I realized I shouldn’t do that any more, because I wasn’t really helping them! They weren’t learning anything, and it would only get harder down the road. Cheating certainly wasn’t helping me.
It takes courage to be honest when people all around you who are getting away with cheating on tests, lying to their parents, and stealing at work. But, remember, every act of honesty is a deposit into your PBA and will build strength.

What does the author expect to show by Jeff’s story

A.Honesty can be of great help.
B.A bad thing can be turned into a good one.
C.Helping others cheat can do good to nobody.
D.One should realize the wrong in his bad deeds.

单项选择题