Exclusive B --> M l^+ l^- (M=\pi, K, \rho, K^*) Decays and Determinations of |V_{ts}| (and |V_{td}/V_{ts}|)

We examine the possibility for precise determination of |V_{ts}| (and |V_{td}/V_{ts}|) from the exclusive decays, $B --> K \ell^+ \ell^-, B --> K^* \ell^+ \ell^-$(and$B --> \pi \ell^+ \ell^-, B --> \rho \ell^+ \ell^-$). We show that the ratio |V_{ts}| can be extracted experimentally with a small theoretical uncertainty from hadronic form–factors, if we {\bf appropriately constrain} kinematical regions of $q^2$. We also give detailed analytical and numerical results on the differential decay width $d\Gamma(B --> K^* \ell^+ \ell^-)/dq^2$,andtheratiosofintegratedbranchingfractions,${\cal B}(B –> \rho \ell^+ \ell^-)/{\cal B}(B --> K^* \ell^+ \ell^-)$. We estimate that one can determine the ratio |V_{ts}| from those decays within theoretical accuracy of $\sim 10$.