for(var i=0;i<Lis.length;i++)    
        {  Lis[i].onmouseover=function (){
           
             var u = this.getElementsByTagName("ul")[0];
             u.style.display = "block";
                    if (u != undefined) {
                        ChangeH(u.id,1);
                    }
           
        }     
               
               
               
               
                Lis[i].onmouseout = function () {
                    var u = this.getElementsByTagName("ul")[0];
                    if (u != undefined) {
                        ChangeH(u.id,-1);
                    }
                }
            }
        }

        function ChangeH(id, count) {
    // 根据ID找到ulList，同时得到其高度
            var ulList = document.getElementById(id);
            var h = ulList.offsetHeight;
   
            h += count;
            if (count > 0) {
                if (h <= 42) {
   // 将高度赋值给ulList，同时，不断调用本函数
                    ulList.style.height = h + "px";
                    setTimeout("ChangeH('" + id + "',1)", 10);
                }
                else {
                    return;
                }
            }
            else {
                if (h > 0) {
  // 将高度赋值给ulList，同时，不断调用本函数
                    ulList.style.height = h + "px";
                    setTimeout("ChangeH('" + id + "',-1)", 10);
                }
                else {
                    ulList.style.display = "none";
                    return;
                }
            }
        }