Formal:
* 您是哪个国家的？ (Nín shì nǎ ge guó jiā de?) - This is the most formal way to ask, literally meaning "Which country are you from?".
* 请问您是哪个国籍的？ (Qǐng wèn nín shì nǎ ge guó jí de?) - This is another formal option, literally meaning "May I ask which nationality you are?".
Informal:
* 你是哪个国家的？ (Nǐ shì nǎ ge guó jiā de?) - This is a more casual way to ask, similar to the formal version but without the honorific "您" (nín).
* 你是什么国籍的？ (Nǐ shì shén me guó jí de?) - This is also a casual option, literally meaning "What nationality are you?".
Other options:
* 你来自哪里？ (Nǐ lái zì nǎ lǐ?) - This literally means "Where are you from?" and can be used to understand someone's nationality.
* 你是哪国人？ (Nǐ shì nǎ guó rén?) - This literally means "Which country's person are you?" and is a more direct way to ask about nationality.
Remember to choose the appropriate level of formality depending on the situation and your relationship with the person you are talking to.