题型:填空题 直流电池组的电动势为E,内电阻为r,用它给电阻为R的直流电动机供电,当电动机正常工作时,电动机两端的电压为U,通过电动机的电流是( )A.ER+rB.URC.E-UrD.E(R+r)Rr 查看答案
题型:填空题 Once she has _____ her mind, nothing can change it. [ ]A. made upB. taken up C. put upD. set up 查看答案