A:broke away from
B:kept away from
C:did away with
D:cut off
解方程组:x-3y-5=03x+4y-2=0.
When do you finish class in the morning?
如图所示的电路,R1=30Ω,R2=10Ω,开关S闭合后,电流表A的示数为0.4A,求:
(1)电源电压.
(2)通过R2的电流.
(3)干路中的电流.