一、datetime模块中日期、时间的表达、比较、差值:
http://www.cnblogs.com/emanlee/p/4399147.html
二、time模块及time与datetime相互转换
http://www.runoob.com/python/python-date-time.html (元组)
http://iam42.iteye.com/blog/1922875
http://www.jb51.net/article/47957.htm