//格式化日期为年4位，月日时分秒为2位的格式
	function formateDate(year,month,day,hour,minute,second){
		if(month<9)month="0"+month;
		if(day<9) day="0"+day;
		if(hour<9)hour="0"+hour;
		if(minute<9)minute="0"+minute;
		if(second<9)second="0"+second;
		return year+"-"+month+"-"+day+" "+hour+":"+minute+":"+second;
	}
	
	//函数调用说明
	//date 格式为2011-08-09 19:21:00，每位数字两个字符，如果是单数，则必须前面加0;
	//field 取值second  minute  hour  day  month  year 
	//n 取值second(-60~60) minute(-60~60) hour(-24~24) day(-31~30) month(-12~12) year(无穷小~无穷大)以上取值区间均不含头尾值。
	function showdate(date,field,n){//date为基数时间格式2011-08-09 19:21:00，n为秒，可正数也可负数
		var date = date.split(' ');
		var time = date[1].split(':');//时间19:21:00
		var date = date[0].split('-');//日期2011-08-09

		var v_second = parseFloat(time[2]);
		var v_minute = parseFloat(time[1]);
		var v_hour = parseFloat(time[0]);
		var v_day = parseFloat(date[2]);
		var v_month = parseFloat(date[1]);
		var v_year = parseFloat(date[0]);
		if(field=='second'){
			if(n>=60)return '';
			if(n<-60)return '';
			v_second = v_second+n;
			if(v_second>=0&&v_second<60){ //  0=<x<60
				return formateDate(v_year,v_month,v_day,v_hour,v_minute,v_second);
			}else if(v_second>-60&&v_second<0){// -60<x<0
				v_second = 60+v_second;
				var temp = formateDate(v_year,v_month,v_day,v_hour,v_minute,v_second);
				return showdate(temp,'minute',-1);
			}else{//因为 控制了n只能在-60到60之间取值（不含首尾），所以上面两个判断之后只剩下了 60=<x<120的可能了
				v_second = v_second-60;
				var temp = formateDate(v_year,v_month,v_day,v_hour,v_minute,v_second);
				return showdate(temp,'minute',1);
			}
		}else if(field=='minute'){
			if(n>60)return '';
			if(n<-60)return '';
			v_minute = v_minute+n;
			if(v_minute<60&&v_minute>=0){// 0=<x<60
				return formateDate(v_year,v_month,v_day,v_hour,v_minute,v_second);
			}else if(v_minute<0&&v_minute>-60){//  -60<x<0
				v_minute = v_minute+60;
				var temp = formateDate(v_year,v_month,v_day,v_hour,v_minute,v_second);
				return showdate(temp,'hour',-1);
			}else{// 60=<x<120
				v_minute = v_minute-60;
				var temp = formateDate(v_year,v_month,v_day,v_hour,v_minute,v_second);
				return showdate(temp,'hour',1);
			}
		}else if(field=='hour'){
			if(n>24)return '';
			if(n<-24)return '';
			v_hour = v_hour+n;
			if(v_hour>=0&&v_hour<24){// 0=<x<24
 				return formateDate(v_year,v_month,v_day,v_hour,v_minute,v_second);
			}else if(v_hour>-24&&v_hour<0){// <-24x<0
				v_hour = v_hour+24;
				var temp = formateDate(v_year,v_month,v_day,v_hour,v_minute,v_second);
				return showdate(temp,'day',-1);
			}else{// 24=<x<48
				v_hour = v_hour -24;
				var temp = formateDate(v_year,v_month,v_day,v_hour,v_minute,v_second);
				return showdate(temp,'day',1);
			}
		}else if(field=='day'){
			if(n>31) return '';
			if(n<-31)return '' ;
			v_day = v_day+n;
			var flag = false;//平润年标致 true表示是闰年
			if(v_year%4==0&&v_year%100!=0||v_year%400==0)flag=true;
			if(v_month==2){
				if(flag){//2月闰年
					if(v_day<=29&&v_day>0){ //0<x<=29&&闰年&&2月份
						return formateDate(v_year,v_month,v_day,v_hour,v_minute,v_second);
					}else if(v_day>-29&&v_day<=0){// -29<x<=0&&闰年&&2月份
						v_day = v_day + 31;//本月是二月份，向前一个月份借一个月，借的是一月份，一月份有31天
						var temp = formateDate(v_year,v_month,v_day,v_hour,v_minute,v_second);
						return showdate(temp,'month',-1);
					}else{// 29<x<(29+31)&&闰年&&2月份
						v_day=v_day-29;
						var temp = formateDate(v_year,v_month,v_day,v_hour,v_minute,v_second);
						return showdate(temp,'month',1);
					}
				}else{//2月非闰年
					if(v_day<=28&&v_day>0){//0=<x<=28&&平年&&2月
						return formateDate(v_year,v_month,v_day,v_hour,v_minute,v_second);
					}else if(v_day>-28&&v_day<=0){//-28<x