Towards Precise Determinations of the CKM Matrix without Hadronic Uncertainties

We illustrate how the measurements of the CP asymmetries in $B^0_{d,s}$-decays together with a measurement of $Br(K_L\to \pi^\circ\nu\bar\nu)$ or $Br(K^+\to \pi^+\nu\bar\nu)$ and the known value of $\mid V_{us}\mid $ can determine all elements of the Cabibbo-Kobayashi-Maskawa matrix essentially without any hadronic uncertainties. An analysis using the ratio $x_d/x_s$ of $B_d-\bar B_d$ to $B_s-\bar B_s$ mixings is also presented.