(1)R=220^2/275=176欧（2）I=P/U=（50+60）/220=0.5A(3)W==Pt=2X275WX10X60S=330000J(4)L1L2左端与S1右端连接,L3L4左端与S2右端连接,换气扇与S3连接,照明灯与S4连接.
