“…Also, the explicit formulas may provide physical information and help us to understand the mechanism of related physical models. Recently, many kinds of powerful methods have been proposed to find exact solutions of nonlinear partial differential equations, e.g., the tanh-method [1], the homogeneous balance method [2], homotopy analysis method [3,4,5,6,7,8,9], the F −expansion method [10], three-wave method [11,12,13], extended homoclinic test approach [14,15,16], the ( G G )−expansion method [17] and the exp-function method [18,19,20,21,22]. The outline of the present paper is as follows.…”