  Using a data set of 2.92 $fb^{-1}$ of $e^+e^-$ collisions at the $\Psi$(3770)
mass accumulated with the BESIII experiment we present preliminary results from
our study of the singly Cabibbo-suppressed decays $D\to\omega\pi$ and the decay
of $D^0\to K_S^0K^+K^-$. The decay $D^+\to\omega\pi^+$ is observed for the
first time with a significance of 5.4$\sigma$ and we find evidence of
4.1$\sigma$ for the decay $D^0\to\omega\pi^0$. As a cross-check the branching
fraction $D\to\eta\pi$ is measured and is found to be compatible with the
current PDG value. The branching fraction of the decay $D^0\to K_S^0K^+K^-$ is
measured in an untagged analysis with 11743$\pm$113 signal events and is found
to be (4.622$\pm$0.045(stat.)$\pm$0.181(sys.))$\times 10^{-3}$. This is
compatible with previous measurements but with significant improved precision.
