their

如果您还是不理解的话，就请看看繁体是怎么翻译的吧。

自己看/qqq里的提示：

This message uses the singular "they", "their", "them" or "themself" as a gender-neutral pronoun. This should be translated preserving the singular meaning as fit for your language in a gender-neutral way.

英文维基条目：https://en.wikipedia.org/wiki/Singular_they

当然如果你仍然不理解，随时欢迎到维基百科上开讨论串，我的账号是lt2818。