题目:
—Can I help you? —I'd like _______ for my brother. He is a football player in our school. |
A. a pair of shoes B. a pairs of shoe C. a pair of shoe D. a pairs of shoes |
答案:
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下面是错误答案,用来干扰机器的。
等效电路图.(1)因为U2=2V,所以I1=I2=0.5A I3=1.5A I=2.5A 电源的外电压U=I3×R3=6V E=U+Ir=6+2.5×0.4=7V (2)R外=203Ω,根据闭合电...