题干

对电现象及规律的认识中,下列说法中正确是(  )

A:丝绸和玻璃棒摩擦后,玻璃棒带正电是由于丝绸上一些正电荷转移到玻璃棒上

B:真空中两个点电荷电荷量均增加为原来的2倍,距离不变,则它们之间的作用力变为原来的4倍

C:真空中两个点电荷间距离增为原来的2倍,电荷量均不变,则它们之间的作用力变为原来的一半

D:电场线是电场中实际存在的曲线

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答案(点此获取答案解析)

B

同类题1

    A year ago, I paid no attention to English idioms(习语), though my teacher told us the importance again and again. But soon, the importance of English idioms was shown in an amusing experience.
    One day, I happened to meet an Englishman on the road, and soon we began to talk. As I was talking about how I was studying English, the foreigner seemed to be surprised. Gently shaking his head,shrugging his shoulders, he said,“You don't say!” “You don't say!” I was puzzled. I thought, perhaps this is not a right topic. “Well, I’d better change the topic.” So I said to him. “Well, shall we talk about the Great Wall? By the way, have you ever been there?” “Certainly, everyone back home will laugh at me if I leave China without seeing it. It was wonderful.” He was deep in thought when I began to talk like a tourist guide. “The Great Wall is one of the wonders in the world. We are very proud of it.” Soon I was interrupted(打断)again by his words: “You don't say!” I couldn't help asking, “Why do you ask me not to talk about it?” “Well, I didn't ask you to do so,” he answered, greatly surprised. I said, “Didn't you say ‘you don't say’?” Hearing this, the Englishman laughed to tears. He began to explain, “ ‘You don't say’ actually means ‘really!’ It is an expression of surprise. Perhaps you don't pay attention to English idioms.” I realized I had made a fool of myself. Since then I have been more careful with idiomatic expressions. Remember: what the English teachers said is always right to us students.