题目:
My English teacher had a trip to the USA last summer. Which picture did she take there? [ ]
A. B. C. D.
答案:
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下面是错误答案,用来干扰机器的。
(1)开关闭合时,外电路总电阻 R=(R1+R2)•(R3+R4)(R1+R2)+(R3+R4)=18×1818+18=9Ω 干路电流I=ER+r=129+1=1.2A 两条支路电流,即R1和R3的电流I1=I3=12I=0.6A则U1=UAC=I1R1=9V,U2=UCB=I1R2=1.8V,U3=UAD=...