foreach ($comments as $k => &$v){
$s = (int)($nowtime-$v['create_time']);
if((0<$s) && ($s<60)){
$v['time_num'] = $s.'秒前';
}elseif((60<$s) && ($s<3600)){
$mins = $s/60;
$v['time_num'] = floor($mins).'分钟前';
}elseif((3600<$s) && ($s<86400)){
$hours = $s/3600;
$v['time_num'] = floor($hours).'小时前';
}elseif($s>=86400) {
$days = $s / 86400;
$v['time_num'] = floor($days) . '天前';
}
}