Cách sử dụng
The word "thirtieth" is used to talk about something that happens or exists in the position of 30th in a series or a list. For example, if you are talking about the 30th day of the month, you could say "today is the thirtieth of the month." Or, if you are talking about a list of items and something is in the 30th position, you could say "this item is the thirtieth on the list."