选项
A.
A.(dfrac{Kz({rm e}^{-T}+{rm e}^{-2T})}{(z+{rm e}^{-T})(z+{rm e}^{-2T})+Kz({rm e}^{-T}+{rm e}^{-2T})})
B.
B.(dfrac{Kz({rm e}^{-T}+{rm e}^{-2T})}{(z-{rm e}^{-T})(z-{rm e}^{-2T})+Kz({rm e}^{-T}+{rm e}^{-2T})})
C.
C.(dfrac{Kz({rm e}^{-T}-{rm e}^{-2T})}{(z-{rm e}^{-T})(z-{rm e}^{-2T})+Kz({rm e}^{-T}-{rm e}^{-2T})})
正确答案: