The structure 该…了
This structure is used to say it’s someone’s turn or time to do something.
The verb 该 
is often used together with 了 . This structure is used in colloquial speech.
is often used together with 了 . This structure is used in colloquial speech.Scheme
该
...
了
In place of the ellipsis, we can use:
1) a word denoting a person — a noun, a pronoun, a proper noun.
Scheme
该
who
了
Examples
现在该谁了？
Whose turn is it now?
xiànzài gāi shéi le
该你了
It’s your turn
gāi nǐ le
2) a verb or a combination of a verb and an object, which denotes an action.
Scheme
该
verb
(object)
了
Examples
该吃饭了
It’s time to eat
gāi chīfàn le
该给婴儿换尿布了
It’s time to change the baby’s diaper
gāi gěi yīng'ér huàn niàobù le
Sometimes, both a person and an action can be used in one sentence. It mostly happens in questions.
Pay attention
The particle 吗 is usually omitted in these type of questions.
is usually omitted in these type of questions.Examples
该谁请客了？
Whose turn is it to pay the bill?
gāi shéi qǐngkè le