题目内容
A.x-y-1=0 B.x-y+1=0 C.x+y-1=0 D.x+y+1=0
C
在直线
(1)P
(2)P
A.x-y-1=0
B.x-y+1=0
C.x+y-1=0
D.x+y+1=0