DateTime dateMyBirthday = new DateTime(1969,7,22);
DateTime dateNewDate= daeMyBirthday.AddMonths(6);
結果:1/22/1970 12:00:00AM
dteNewDate= dteMyBirthday.AddYears(2);//Returns 7/22/1971 12:00:00 AM
dteNewDate= dteMyBirthday.AddMonths(5);//Returns12/22/1969 12:00:00 AM
dteNewDate= dteMyBirthday.AddMonths (-1);//Returns 6/22/1971 12:00:00 AM
dteNewDate= dteMyBirthday.AddHours (7);//Returns 7/22/1969 12:00:00 AM
