DateTime.Now 输出 09/03/2020 09:45:23
DateTime.Now.Date 输出 09/03/2020 00:00:00
DateTime.Now.ToDateString() 输出 2020-09-03
DateTime.Today 输出 09/03/2020 00:00:00
DateTime.Now.ToLocalTime() 输出 09/03/2020 09:45:23
DateTime.UtcNow 输出 09/03/2020 01:45:23
DateTime.Now.ToLongDateString()输出2020年9月3日
DateTime.Now.ToShortDateString()输出2020/9/3
DateTime.Now.ToLongTimeString()输出9:45:23
DateTime.Now.ToShortTimeString()输出9:45
DateTime.Now.ToUniversalTime()输出09/03/2020 01:45:23
DateTime.Now.ToOADate()输出44077.4065256134
