* [hh] refers to a zero-padded hour between 00 and 24 (where 24 is only used to notate midnight at the end of a calendar day).
* [mm] refers to a minute between 00 and 59.
* [ss] refers to a second between 00 and 60 (where 60 is only used to notate an added leap second).
24:00:00表示midnight,而不是24个小时。