The tracial topological rank of certain C*-algebras

Let 0 → I → A → A/I → 0 be a short exact sequence of C*-algebras with A unital. Suppose that I has tracial topological rank no more than one and A/I belongs to a class of certain C*-algebras. We show that A has tracial topological rank no more than one if the extension is quasidiagonal, and A has the property (P1) if the extension is tracially quasidiagonal.