单项选择题
A.x(t)=1B.C.x(t)=tD.x(t)=e-t
A.a-b=1B.a-b≠1C.a-b=-1D.a-b≠-1
A.a=1,b=1B.a=-1,b=1C.a=-1,b=-1D.a=1,b=-1