题干

下列有关电流、电压、电阻的分析正确的是(  )


A:电压是形成电流的原因,有电压就一定有电流

B:加在导体两端的电压越高,导体中的电流就一定越大

C:当电阻一定时,导体中的电流与这段导体两端的电压成正比

D:白炽灯泡在不同电压下测得的电阻不同,因此导体的电阻与电压有关

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C

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    The Chinese used the abacus as early as the 2nd century BC, but now are welcoming“machine brains”to educate the young in this modern age.

    For the young, e-learning seems so1Zhu Xufei, 12, uses her parents' mobile phone to study English every day on her way to school and back home. Through an app, she can listen to and repeat back words and sentences in English. The app even tells the difference between her speech and proper pronunciation, and then 2 provides the score.

    The mother of 12-year-old Zhu said,“The apps have enabled her to learn and practice spoken English anytime, anywhere,”she says.“The apps also have been designed to use games to encourage learning.”

    It's very popular nowadays, especially with parents. WeChat accounts of parents post progress reports every day on 3their children are doing. For example,“Day 30: My son Thomas has learned 99 English words on Talking Pets.”

    It's not only children using mobile devices(设备)to learn new things. Many Metro or bus passengers can be seen with earplugs turned into app courses, like business management or the driving test.“I don't have to4books around and turn pages on crowded buses,”an office lady says.“With just a touch of the screen on my smartphone, I can do practice tests whenever I have time. It also records my 5 and makes it easier for me to review them.”

    E-learning has been welcomed among education services. Zheng Lili, owner of an English training school, says the learning apps help6 better monitor the performances of students.

    We believe that education should be'whole-person'development and such devices are just support tools.