好的我找到了答案。这将解决它：

Ok I found the answer. This will fix it:

$(document).ready(function()
{  
   $('#topnav ul li ul.submenu li a').click(function(e){
     if ($(this).attr('class') != 'active'){
       $('#topnav ul li a').removeClass('active');
       $(this).addClass('active');
     }
   });
       $('a').filter(function(){
            return this.href === document.location.href;
       }).addClass('active')
       $("ul.submenu > li > a").each(function () {
         var currentURL = document.location.href;
         var thisURL = $(this).attr("href");
         if (currentURL.indexOf(thisURL) != -1) {
             $(this).parents("ul.submenu").css('display', 'block');
         }
       });
       $('#topnav > ul > li > a').each(function(){
      var currURL = document.location.href;
      var myHref= $(this).attr('href');
      if (currURL.match(myHref)) {
            $(this).addClass('active');
            $(this).parent().find("ul.submenu").css('display', 'block');
      }
    });
});