<div class="zy_menu clearfix">
<a href="javascript:;" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="1" id="assoeted1" class="hover_a">課件庫</a> <a href="javascript:;" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="2" id="assoeted2">課堂實錄</a> <a href="javascript:;" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="3" id="assoeted3">試題庫</a> <a href="javascript:;" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="4" id="assoeted4">教案庫 </a> <a href="javascript:;" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="5" id="assoeted5">素材庫 </a>
</div>

var assoeted =5;

$(".zy_menu a[rel="+assoeted+"]").removeClass("hover_a").addClass("hover_a");
$(".zy_menu a").removeClass("hover_a").eq(assoeted-1).addClass("hover_a");