问题 多选题

如图所示,A、B为两个等量同种点电荷,a、O、b在点电荷A、B的连线上,c、O、d在连线的中垂线上Oa=Ob=Oc=Od,则(  )

A.a、b两点的场强相同,电势也相同

B.c、d两点的场强不相同,电势相同

C.O点是A、B连线上电势最低的点,也是A、B连线上场强最小的点

D.O点是中垂线cd上电势最高的点,也中垂线上场强最大的点

答案

作出两个电荷连线上的电场线和中垂线上电场线如图.

A、根据电场线分布可知,a、b两点场强方向相反,则场强不同;由电场线的方向可知,c点电势等于d点电势.故A错误.

B、根据电场线分布可知,a、b两点场强方向相反,则场强不同;由电场线的方向可知,c点电势等于d点电势.故B正确.

C、由图可知,o点电势是AB连线上的最低点,同时根据电场强度的叠加可知,O点的电场强度是A、B连线上最小点.故C正确.

D、根据图可知,O点是中垂线cd上电势最高的点,但不是中垂线上场强最大,而是最小.故D错误.

故选BC

阅读理解

阅读理解。

      To what degree can a computer achieve intelligence (智力)? The answer to this question may lie in a

newly-developed US computer program called Smarter Child and the Internet. 

       If you ran into Smarter Child online, you would be surprised at this kid's huge memory. It can recite

many facts. For example, Smarter Child knows every baseball player in every team this season. 

       He knows every word in the dictionary and the weather in every major city areas across the US.

However, if you ask Smarter Child other questions, you get stranger answers. A question about Smarter

Child's age returns. "One year, 11 days, 16 hours, 7 minutes, and 47 seconds!" Asking where he lives gets,

"In a clean room in a high-tech building in California."

       Smarter Child uses the vast information on the World Wide Web as his memory bank. To answer

questions about spelling, for instance, Smarter Child goes to American Heritage Dictionary online. For the

weather, he visits www.intellicast.com. 

       Some scientists believe that by joining the many systems of the Internet, an artificial being with the

combined knowledge of, say, Albert Einstein, Richard Nixon and Britney Spears could be born. However

if Smarter Child wants to think and learn on his own like the boy-computer David in the movie A.I.,

Artificial Intelligence, he must overcome two problems. 

       The first is that computers find it difficult to read web pages because the files are labeled in different

ways. That's why programmers need to tell Smarter Child where to look for the weather. It would be a

much more difficult task to let him find it himself.

       Another problem is that while Smarter Child can process (处理) information more exactly and faster

than any human, he lacks common sense-a basic grounding of knowledge that is obvious to any young

child.

1. From the text we can infer that www.inte3llicast.com is a website _____. [ ]

A. which is specially designed to help Smarter Child

B. where we people can find Smarter Child

C. where weather forecasts are made

D. which is about artificial intelligence

2. It is probably most difficult for Smarter Child to _____.[ ]

A. tell us how to spell a difficult word

B. tell us how the American government is run

C. provide us with a famous poem by Shakespeare

D. learn how to tell right behaviors from wrong ones.

3. Which of the following is TRUE according to the text? [ ]

A. Smart Child has his own memory bank big enough for all kinds of information.

B. A.I. Artificial Intelligence is probably the name of a film about a boy-computer.

C. Smart Child can recognize different files and find information needed on his own.

D. We have similar product now which has the knowledge of Einstein, Nixon and Spears.

4. Which of the following is the bet title for the passage? [ ]

A. A New Web Child

B. Smarter Child

C. The Future of Internet

D. Intelligence Development

判断题