Как по Английски будет 他们的

possessive determiner

Belonging to or associated with the people or things previously mentioned or easily identified.

Примеры использования:

Parents are keen to help their children

pronoun

Belonging to or connected with them; the possessive form of they, used before a noun

Примеры использования:

It was their money, and they could spend it as they liked., someone forgot to take their umbrella.

possessive pronoun

Used to refer to a thing or things belonging to or associated with two or more people or things previously mentioned.

Примеры использования:

They think everything is theirs

pronoun

Belonging to them, or that which belongs to them

Примеры использования:

Here’s my car. where’s theirs?