Exclusive and inclusive semileptonic decays of<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mi>B</mml:mi></mml:math>mesons to<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mi>D</mml:mi></mml:math>mesons

We report new measurements of the branching fractions $B({B}^{\ensuremath{-}}\ensuremath{\rightarrow}{D}^{0}{l}^{\ensuremath{-}}\overline{\ensuremath{\nu}})$, $B({\overline{B}}^{0}\ensuremath{\rightarrow}{D}^{+}{l}^{\ensuremath{-}}\overline{\ensuremath{\nu}})$, and $B({B}^{\ensuremath{-}}\ensuremath{\rightarrow}{D}^{*0}{l}^{\ensuremath{-}}\overline{\ensuremath{\nu}})$. Combining these results with our previous measurement of $B({\overline{B}}^{0}\ensuremath{\rightarrow}{D}^{*+}{l}^{\ensuremath{-}}\overline{\ensuremath{\nu}})$, we find that the ratio of semileptonic widths for final states with a vector meson and pseudoscalar meson is (${2.6}_{\ensuremath{-}0.6\ensuremath{-}0.8}^{+1.1+1.0}$) and the ratio of charged- to neutral-$B$-meson lifetimes is $(0.89\ifmmode\pm\else\textpm\fi{}0.19\ifmmode\pm\else\textpm\fi{}0.13)(\frac{{f}_{00}}{{f}_{+\ensuremath{-}}})$ where ($\frac{{f}_{00}}{{f}_{+\ensuremath{-}}}$) is the ratio of neutral- to charged-$B$-meson production at the $\ensuremath{\Upsilon}(4S)$. From the $\overline{B}\ensuremath{\rightarrow}D{l}^{\ensuremath{-}}\overline{\ensuremath{\nu}}$ branching fraction, we calculate $|{V}_{\mathrm{cb}}|=0.040\ifmmode\pm\else\textpm\fi{}0.006\ifmmode\pm\else\textpm\fi{}0.006$, where the first error is statistical and the second is systematic and dominated by the uncertainty in the $B$-meson lifetime.