题干

关于电源的电动势,下列说法正确的是(   )

A:电源的电动势就是接在电源两极间的电压表测得的电压

B:同一电源接入不同的电路,电动势就会发生变化

C:电源的电动势是表示电源把其他形式的能转化成电能的本领大小的物理量

D:在闭合电路中,当外电阻变大时,路端电压增大,电源的电动势也增大

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答案(点此获取答案解析)

C

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    "You should get in touch with other young people," his mother told him, with a kindness in her heart. The boy's father talked with the family doctor about his ears. "Could nothing be done?"the father asked. "I believe I could give him a pair of outer ears, if they could be got," the doctor replied.
    Two years went by. One day, his father said to the son, "You are going to the hospital, Son. Mother and I have someone who will donate the ears you need, but it's a secret."The operation is a big success. Later he married and entered the diplomatic(外交的) service. One day, he asked his father, "Who gave the ears? Who gave me so much? I could never do enough for him or her."
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