PHP's processing of time (year, month, week, day, hour, minute, second)

<span style="color:#555555">".$nowtime."";
echo "
距".strftime("%Y-%m-%d ",$date1)."还有".$days."天


";

echo "当前时间   " . date("Y-m-d h:i:s",strtotime("now")). "
";
echo "后天时间   " . date("Y-m-d h:i:s",strtotime("+2 day")). "
";
echo "下周时间   " . date("Y-m-d h:i:s",strtotime("+1 week")). "
";
echo "下月时间   " . date("Y-m-d h:i:s",strtotime("+1 month")). "
";
echo "明年时间   " . date("Y-m-d h:i:s",strtotime("+1 year")). "
";
echo "下周2天4小时2秒后的时间   " . date("Y-m-d h:i:s",strtotime("+1 week 2 days 4 hours 2 seconds")). "
";
echo "下周四时间   " . date("Y-m-d h:i:s",strtotime("next thursday")). "
";
echo "上周一时间   " . date("Y-m-d h:i:s",strtotime("last monday")). "
";
echo "2015-01-04  3天后的时间   " . date("Y-m-d h:i:s",strtotime("+3 day",strtotime('2015-01-04')));

?></span>