  In this paper, we will prove several new inequalities of Hardy's types with
explicit constants. The main results will be proved by making use of some
generalizations of Opial's type inequalities and H\"older's inequality. To the
best of the author's knowledge this method has not been used before in
investigation of this type of inequalities. From these inequalities one can
establish some new inequalities of differential forms which are inequalities of
Wirtinger's typ
