题干

下列关于电动势的说法正确的是(  )

A:电源的电动势跟电源内非静电力做的功成正比,跟通过的电荷量成反比

B: 只是电动势的定义式而非决定式,电动势的大小是由电源内非静电力的特性决定的

C:非静电力做的功越多,电动势就越大

D:电动势的单位跟电压的单位一致,所以电动势就是两极间的电压

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答案(点此获取答案解析)

B

同类题2

阅读下面短文,然后回答问题。

    Wang Fei,a Chinese student,and Mary,an American student studying Chinese in China,were in a supermarket.They saw a young man walking down the stairs.In his hurry,he missed the last two steps and fell onto the ground.He tried to stand up while people around him laughed.Luckily,he seemed to be OK.

    Mary found Wang Fei smiling a little and was not happy about it. “Tell me, Fei, how could people laugh when someone fell like that? Why didn't they go up and ask him if he was hurt?”

    Wang Fei said, “Because they knew he wasn't hurt too much.”

    “But I still don't understand.A fall is a fall.In my culture, people would never laugh!”

    This is an example.The Chinese and the westerner will think and act differently when seeing such a thing.Chinese people are used to laughing or smiling.Very often the person who is in embarrassing(困窘的)situation would also laugh or smile to get out of it.However,if someone gets hurt seriously,it will not be a laughing matter any more.People will help him or her instead.

    But,in that case,a westerner will rush over and help the person get up.If a westerner falls,he or she,like a Chinese person,may try to make a joke if he or she is not hurt.If two close friends are walking together,and one falls but clearly isn't hurt,a common joke is to say “Have a nice trip”.

    So different people have different habits and different countries have different cultures