  We show that there is a residual subset $\mathcal{R}$ of $Diff^1(M)$ such
that for any $f\in\mathcal{R}$ and any partially hyperbolic homoclinic class
$H(p,f)$ with one dimensional center direction, the set of central Lyapunov
exponents associated with the ergodic with either full support or positive
entropy is an interval.
