单项选择题
A.y(n)+0.5y(n-1)=0.5x(n)B.y(n)-0.5y(n-1)=0.5x(n)
A.h(n)=[1,0.2,-1,0,1,0.2,-1]B.h(n)=[1,0.2,-1,0,1,-0.2,-1]C.h(n)=[1,0.2,-1,3,1,-0.2,1]D.h(n)=[1,0.2,-1,3,-1,0.2,-1]
A.1B.δ(n-3)C.δ(n-2)D.δ(n-2)-δ(n-3)