题干

对欧姆定律变形公式R=
U
I
的理解,下面的哪一句话是正确的?(  )

A:导体两端的电压越大,导体的电阻越大

B:通过导体的电流越小,导体的电阻越大

C:导体的电阻既与导体两端的电压有关,也与通过导体的电流有关

D:电阻是导体本身的一种性质,它两端的电压与通过其的电流比值是一定的

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答案(点此获取答案解析)

D

同类题1

阅读理解。

On one of her trips to New York several years ago, Eudora Welty decided to take a couple of New York friends out to dinner. They settled in at a comfortable East Side cafe and within minutes, another customer was approaching their table.

      “Hey, aren't you from Mississippi?” the elegant, white-haired writer remembered being asked by the stranger. “I'm from Mississippi too.”

      Without a second thought, the woman joined the Welty party. When her dinner partner showed up, she also pulled up a chair

      “They began telling me all the news of Mississippi,” Welty said. “I didn't know what my New York friends were thinking.”

Taxis on a rainy New York night are rarer than sunshine. By the time the group got up to leave, it was pouring outside. Welty's new friends immediately sent a waiter to find a cab. Heading back downtown toward her hotel, her big-city friends were amazed at the turn of events that had changed their Big Apple dinner into a Mississippi.

      “My friends said: 'Now we believe your stories,'” Welty added. “And I said: 'Now you know. These are the people that make me write them.'”

      Sitting on a sofa in her room, Welty, a slim figure in a simple gray dress, looked pleased with this explanation.

      “I don't make them up,” she said of the characters in her fiction these last 50 or so years. “I don't have to.”

Beauticians, bartenders, piano players and people with purple hats, Welty's people come from afternoons spent visiting with old friends, from walks through the streets of her native Jackson, Miss., from conversations overheard on a bus. It annoys Welty that, at 78, her left ear has now given out. Sometimes, sitting on a bus or a train, she hears only a fragment(片段) of a particularly interesting story.