if (N == 2) {
            if (this._y>250) {
                this._x -= guaiwu_xmove;
                this._y -= guaiwu_ymove;
            } else {
                this._x += guaiwu_xmove;
                this._y -= guaiwu_ymove;
            }
        }
如果需要怪物斜着从怪物从上面飞进从上面飞出，并且设定它的代号为3，即N==3那么我的代码是这么写的：                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                               Flash射击游戏设计+需求分析(11):http://www.youerw.com/jisuanji/lunwen_464.html