｜x+1/2|与|y-1/2|互为相反数=>｜x+1/2|=0 and ｜y+1/2|=0x=-1/2 and y=1/2x-(-y)=-1/2 -(-1/2)=0
x=-1/2，y=1/2x+y=0
∵｜x+½|与|y-½|互为相反数;∴∣x+1/2∣+∣y-1/2∣=0∴x=-1/2，y=1/2;于是x-(-y)=x+y=-1/2+1/2=0
