问题 选择题

在静电场中,下列说法中正确的是(  )

A.电场强度为零的点,电势也一定为零

B.电场强度处处相等的区域内,电势也一定处处相等

C.只在电场力作用下,正电荷一定从电势高的地方向电势低的地方移动

D.沿着电场线方向电势一定越来越低

答案

A、电场强度为零的点,电势不一定为零,电势的零点可以人为选择.故A错误.

B、电场强度处处相等的区域内,顺着电场线方向的两点电势会降低,同一等势面的各点电势相等,所以电势不一定处处相等.故B错误.

C、只在电场力作用下,电荷移动方向与电荷有没有初速度,初速度的方向怎样有关,所以正电荷不一定从电势高的地方向电势低的地方移动,故C错误.

D、沿着电场线方向电势一定越来越低.故D正确.

故选D

阅读理解

This is news on the Hour, Ed Wilson reporting. The president and First Lady will visit Africa on a goodwill tour in May. They plan to visit eight African countries.

Reports from Chinese want close ties between China and the US and Western Europe. A group of top Chinese scientists start in ten-nation tour next month.

Here in Miami, the mayor is still meeting with the leaders of the Teachers’ Union to try to find a way to end the strike. City schools are still closed after two weeks.

In news about health, scientists in California report findings of a relationship between the drinking of coffee and the increase of heart disease among women.  According to the report in the American Medical Journal (杂志), the five-year study shows this: Women who drink more than two cups of coffee a day have a greater chance of having heart disease than women who do not.

In sports, the Chargers lost again last night. The BBS beat them 1 to nothing. The Wingers had better results. They beat the Rifles 7 to 3. It was their first win of their last five matches. That’s the news of the Hour. And now back to more easy listening with Jan Singer.

小题1:To improve the ties between China and the US and Western Europe, China ______.

A.will send a group of Chinese scientists to visit the US and. Western Europe

B.has expressed its strong wishes

C.will send some scientists to visit the US only

D.has given many reports to improve the ties小题2:From the news in Miami we know ______.

A.a peaceful way will soon be found

B.students can’t go into the school because the classrooms are locked

C.students haven’t been to school for two weeks

D.the teachers’ strike will last long小题3:The news about health tells us that ______.

A.no heart disease will be found if people don’t drink coffee

B.no one should drink more than two cups of coffee a day

C.the more coffee people drink, the more chance they’ll get to have heart disease

D.women’s heart disease has something to do with their drinking coffee小题4:From the last news we do not know ______.

A.the results of the two matches

B.the number of the teams which played last night

C.how many wins the BBS has had altogether

D.the Wingers played against the Rifles

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