Question

1.4 in the text says that "Máng ma?" is "Are [you] busy?" because the pronoun is usually implied and therefore omitted. Where would you put "nǐ" to clarify the subject? Is "Nǐ máng ma?" correct?

Answer 1

Yes, that's correct, you would say Nǐ máng ma? or You busy? The pronoun goes first in this type of question.

Answer 2

Ohh okay, so it also says that one replies with "Hěn máng," but you can also reply with "Wǒ hěn máng" then, right?

Answer 3

Yes that's correct too. It is usually used when you have a dialogue like:
A: Nǐ máng ma?
B: Hěn máng, Nǐ ne?
A: Wǒ ye hěn máng.
if not, Hěn máng is sufficient :)