答案选B.因为|x-2y|+(x+y-3)^2=0,又因为|x-2y|≥0,(x+y-3)^2≥0,所以|x-2y|=0且(x+y-3)^2=0,所以有x-2y=0,(1)x+y-3=0,(2)由(1)得x=2y,(3)把(3)代入(2)得3y-3=0,所以y=1,所以x=2,所以x^y=2^1=2....