var dateOnly = new DateTime(2021, 10, 1);
//輸出
2021/10/1 0:00:00
//問題：還是有時間，并不能代表0點出生

var timeOnly = new TimeSpan(11, 22, 0).Add(TimeSpan.FromHours(24));
//輸出
1.11:22:00
//問題：過了24小時，應該還是當前時間，實際帶了天數(shù)

var dateOnly = new DateOnly(2021, 10, 1);
//輸出
10/1/2021

var timeOnly = new TimeOnly(11, 22, 0);
//輸出
11:22 AM

var datetime = new DateTime(2021, 10, 1, 10, 1, 0);

var dateOnly = DateOnly.FromDateTime(datetime);

var timeOnly = TimeOnly.FromDateTime(datetime);

var timeSpan = new TimeSpan(11, 22, 0);
?
var timeOnly = TimeOnly.FromTimeSpan(timeSpan);

var dateOnly = new DateOnly(2021, 10, 1);

var timeOnly = new TimeOnly(11, 22, 0);

var datetime = dateOnly.ToDateTime(timeOnly);
//輸出
10/1/2021 11:22:00 AM

var timeOnly = new TimeOnly(11, 22, 0);

var timeSpan = timeOnly.ToTimeSpan();
//輸出
11:22:00

var noon = new TimeOnly(12, 0);
if (now < noon)
{
? ? //早上
? ? ...
}

dateOnly = dateOnly.AddDays(7);

timeOnly = timeOnly.AddHours(24);