“…This causes some mathematical difficulties which make the study of (1.3) particularly interesting. In the past few years, The problem (1.3) has been studied by many authors, for example [1,4,5,6,7,13,14,15,16,17,20,21,22]. Many solvability conditions on the nonlinearity f near zero and infinity for the problem (1.3) have been considered, such as the superlinear case [14] and asymptotical linear case [17].…”