D/C in that order would be
x 3 0 2 3 x
(x meaning you don't strum those string)
and D/B is
x 2 0 2 3 x
All those two chords do is to take a plain D major, and then put a different bass note under it, first a C (third fret on the second string), then a B (second fret on the second string).