a点电压=10v x 300/(100+300) = 7.5v
b点电压= 10v x 50/(100+50) = 10v/3
Uoc=Uab=7.5-3.3=4.2v
Req=Rab(10v电压源置短路)=(100//300)+(100//50)
=300/4 + 100/3
=75+33.3=108.3欧
