Why can't I say "cây o" ? Aren't o and dù the same ?
It's "ô". Yes, ô and dù are the same. Ô is the way the North people say umbrella, Dù is the way the South say it
So it can almost never be [zu], right?)) I mean it's pronounced [ju].
What exactly is the classifier cây used for?
cây = a tree, a stick, a baton, a cane - just about anything long, straight, and solid, and made of wood.
It's not necessary that it made of wood ^^ Any thing long, straight and solid are enough ^^
oh, that makes sense now
and also for musical instruments, particularly string instruments.
He says 'zoh'. Like 'o'. Not 'zoo' like 'u'.
To me it sounds slightly diphthongized, approaching [ʊu̯], but still far from [o].