  Permutation polynomials over finite fields constitute an active research area
and have applications in many areas of science and engineering. In this paper,
four classes of monomial complete permutation polynomials and one class of
trinomial complete permutation polynomials are presented, one of which confirms
a conjecture proposed by Wu et al. (Sci. China Math., to appear. Doi:
10.1007/s11425-014-4964-2). Furthermore, we give two classes of trinomial
permutation polynomials, and make some progress on a conjecture about the
differential uniformity of power permutation polynomials proposed by Blondeau
et al. (Int. J. Inf. Coding Theory, 2010, 1, pp. 149-170).
