A.a=-4,b=1
B.a=4,b=-7
C.a=0,b=-3
D.a=b=1
[单选题]A.a=-4,b=1B.a=4,b=-7C.a=0,b=-3D.a=b=1
[多选题]A.B.C.D.E.
[单选题]A.B.C.D.