如果|x﹣3|+|y+1|=0,那么x﹣y等于( )
A:-4
B:4
C:2
D:-2
It is reported that a new shopping mall will be built in ________ was farmland decade ago.
如图所示的电路中,电源电压不变,电阻R1的阻值为20Ω.当断开开关S1和S2,闭合开关S3时,电流表的示数为0.50A;当断开开关S2,闭合开关S1、S3时,电流表的示数为0.90A.求:
下列中,( )属于自行车的控制部分。