shéi?
Who?
哪里?
Where?
哪里 is a compound of 哪 (nǎ) "which" and 里 (lǐ) "inside," but together it simply means "where." It's a fixed question word.
在哪里?
zài nǎlǐ?
Where is it? — More polite, specifying location.
你在哪里?
nǐ zài nǎlǐ?
Where are you? — Casual, personal question.
你在哪里?
Nǐ zài nǎlǐ?
Where are you?
我在学校。
Wǒ zài xuéxiào.
I'm at school.
Appropriate
Avoid when
You say 哪里 (nǎlǐ?). It is the standard word for 'where'.
It is pronounced 'nǎlǐ?' with the third tone on both syllables.
Use 哪里 to ask about a location, such as in 你住在哪里? (Where do you live?). It is neutral and widely used.
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