Did anyone write "Cái mũ màu trắng..." ? Is 'màu' unnecessary when it's an adjective?
It can be omitted, yes. Cái mũ màu trắng is accepted now.
cái nón trắng là của ai ?
Mũ and nón is actually synonyms. And should be correct :)
Why is 'non' not accepted?
Please accept 'nón có màu trắng của ai?'.
Is "Whose is the white hat?" a valid English question?
I see the reply from David480743. But in normal American conversation, we would say, "Whose blue mug is that?", not "Whose is the blue mug."
Yes, absolutely standard , cf 'Whose is the blue mug ?' Whose is the blue car blocking mine?' etc
Is chiếc still mandatory after three years?
Not now, happy to report.
I copy and pastes the translation. This is hard.