  We obtain a class of examples of non-rational adjoint classical groups of
type $^2A_n$ and a group of type $^2D_3$ over the function field $F$ of a
smooth geometrically integral curve over a $p$-adic field with $p \neq 2$. We
also show that for any group of type $C_n$ over $F$, the group of rational
equivalence classes of $G$ over $F$ is trivial, i.e., $G(F)/R=(1)$.
