When do you know when to use "sua" instead of "teu"
When is it appropriate to use 'teu' and 'tua'?
When it is related to "tu"
Why is it not 'A sua chave' please?
It's also right.
But I have a question, I wrote "Seu chave" and it hasn't been correct. is it correct or not? Thanks.
It's not correct. "Chave" is a feminine noun, so you should use "sua".
Seu is in case of words with artikel "o".
It is not correct
Could I have written Tua chave and been correct?
Yes, it is also right.