U2=9V+9V-12V=6V
U1=9V-6V=3V R1=3V/12V*24=6
U3=9V-6V=3V R3=3V/12V*24=6
A1测R3,I3'=12V/6=2A
A2测R1,I1'=12V/6=2A
所以A1、A2示数均为2A