A.T1+T2-T1*T2 B.(T1*T2)/(T1+T2) C.(T1+T2)/(T1*T2) D.T1+T2-(T1*T2)/(T1+T2)
A.R1+R2-R1*R2 B.(R1*R2)/(R1+R2) C.(R1+R2)/(R1*R2)
A、星形網 B、復合形網 C、環(huán)形網