This sentence sounds unnatural for me. I usually say ''Bạn sai rồi''.
"Bạn sai" is fine. "Bạn sai. Tôi đúng." :-)
It's OK, I meant that ''Bạn sai rồi'' is better'. I think it's a bit rude to say ''Bạn sai''.
The problem is that rồi will be somewhere later in the lessons. They couldn't introduce it here.
Amusingly, sai is Malaysian for ‘shit’, hence the Singaporean phrase ‘kena sai’ (lit ‘encounter shit’, i.e. get screwed). So you’re either dung or sai.
Nice, another polyglot! :)
You are incorrect?