var snum=1; //初始化显示的图片
          var best_num=4; //图片的数量
          var sec=2500; //切换图片的速度
          var pic_id;
          function FocusSlide(v){
          	var i;
            for(i=1;i<=4;i++){
          	  eval("document.getElementById(\"focus_tit_"+i+"\").className=\"\"");
          	  eval("document.getElementById(\"focus_img_"+i+"\").style.display=\"none\"");
          	}
			eval("document.getElementById(\"focus_tit_"+v+"\").className=\"acti\"");
			eval("document.getElementById(\"focus_img_"+v+"\").style.display=\"\"");
            SetNum(v+1);
            clearTimeout(pic_id);
            pic_id = setTimeout("FocusSlide(snum)",sec);
          }
          function SetNum(v){
            snum=v;
            if(snum>best_num) snum=1;
          }
          pic_id = setTimeout("FocusSlide(snum)",sec);