  In the current article, we prove the cross product $C^*$-algebra by a Rokhlin
action of finite group on a strongly quasidiagonal $C^*$-algbra is strongly
quasidiagonal again. We also show that a just-infinite $C^*$-algebra is
quasidiagonal if and only if it is inner quasidiagonal. Finally, we compute the
topological free entropy dimension in just-infinite $C^*$-algebras.
