大黄酚的结构A. R1 =CH3 R2 =HB. R1 =CH2OH R2=HC. R1 =CO

有三个电阻R1、R2、R3并联，则并联总电阻R与R1、R2、R3的关系是（)。A.R=R1＋R2＋R3B.1／R=1／R1＋1／R2＋1／

在一电路中，总电阻R与各分电阻R1、R2满足1／R=1／R1＋1／R2，则该电路是（)。A.串联B.并联C.混联

大黄素的结构A. R1 =CH3 R2 =HB. R1 =CH2OH R2=HC. R1 =CO

芦荟大黄素的结构A. R1 =CH3 R2 =HB. R1 =CH2OH R2=HC. R1 =

大黄酚的结构A. R1 =CH3 R2 =HB. R1 =CH2OH R2=HC. R1 =CO

大黄素的结构A. R1 =CH3 R2 =HB. R1 =CH2OH R2=HC. R1 =CO