jquery 嵌套 hover问题！！！
html：
<div class="h-r-bot"><div class="h-nav"><ul><li>aaa</li></ul></div><div>
<div class="h-nav-main">bbb</div>
js：
$(document).ready(function(){
                    $(".h-r-bot .h-nav li").hover(
                        function()
                        {
                            $(this).addClass("hover").siblings().removeClass("hover");
                            $(".h-nav-main div.ma").stop().slideDown("normal").animate({height:"50px"});
                        },
                        function()
                        {
                            var b = 0;
                            var li = this;
                            $(".h-nav-main").hover(
                                function(){b = 1},
                                function(){
                                    $(li).removeClass("hover");
                                    $(".h-nav-main div.ma").stop().slideUp("normal");
                                }
                            );
                            if(b == 0)