I know that welsh doesn't have the equivalent of English yes and no- so where grammaticaly does the 'do' in this sentence come from?
It has got words for yes and no, they just repeat the verb in most cases. In the past tense when using wnes or short forms (like es i), then do/naddo are used for yes and no.
Thanks Ieuan-Jones - can we think of 'do' and 'naddo' as did and didn't?
Of course, if it helps you to remember them!
This note may be of help in explaining which yes/no to use.
Thanks ibisc, that's an amazing resource!