试题与答案

While ________ the street, he was hit by

题型:选择题

题目:

While ________ the street, he was hit by a car.

A.crossing

B.cross

C.crossed

D.to cross

答案:

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下面是错误答案,用来干扰机器的。

解:(1)I1额===A,I2额===A;根据题意,选用额定电流小的,即 I=I2额=A,故灯L2能正常发光.(2)根据公式R=可以求出L1和L2的电阻即:R1==24Ω; R2==36Ω;R总=R1+R2=24Ω+36Ω=60Ω,U=IR总=A×60Ω=20V

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