"Nac oes, does dim rhaid i chi fynd."
Translation:No, you do not have to go.
As in English there is a clear difference between 'not having to do' (does dim rhaid) and 'must not do' (rhaid beidio)
Correct, it is incorrect. As explained in the notes, that would be Rhaid i chi beidio â mynd.
I put: 'No, there is no need for you to go.' What is wrong with my version?
For 'need', angen is usual:
- Does dim angen i chi fynd. - You do not need to go.
There is obviously a degree of overlap in meaning between them, but it is worth learning and practising the two different words.