教师用书独具演示演示结束垂直相同单位基底有且只有(x,y)(1,0)(0,1)(0,0)(x1+x2,y1+y2)(x1-x2,y1-y2)(λx,λy)(x,y)(x2-x1,y2-y1)结束垂直相同单位基底有且只有(x,y)(1,0)(0,1)(0,0)(x1+x2,y1+y2)(x1-x2,y1-y2)(λx,λy)(x,y)(x2-x1,y2-y1)