方案解决目标：计算时间差异

function ago($time){
   $periods = array("second","minute","hour","day","week","month","year","decade");
   $lengths = array("60","60","24","7","4.35","12","10");

   $now = time();

       $difference     = $now - $time;
       $tense         ="ago";for($j =0; $difference >= $lengths[$j]&& $j < count($lengths)-1; $j++){
       $difference /= $lengths[$j];}

   $difference = round($difference);if($difference !=1){
       $periods[$j].="s";}return"$difference $periods[$j] 'ago' ";}