2x/(x-y)额，我算错了。。还是给我过程吧，给你分｛2/3x-[2/(x+y)]×[(x+y)/3x]+[2/(x+y)]×(x+y)｝/[(x-y)/x]=(2/3x-2/3x+2)/[(x-y)/x]=2x/(x-y)