Eight years on… I’ve just seen this and it made me laugh a lot. Diolch! (I still don’t know all the ways to say yes and no, though)
I find it easier to think that most of the time there isn’t a word for ‘yes’ or ‘no’ - you have to either agree or disagree with the question, e.g.
“Were you going to town?” - “I was” (O’t ti’n mynd i’r dre? - O’n)
“Has he seen the film?” - “He has” (Yw e wedi gweld y ffilm? - Ydy)
That way you don’t need to follow the “listen to the beginning of the question” advice to answer. You just think what YOU actually want to convey, and say that, as if there were no “Yes” or “No” on the front.
This makes perfect sense… the only thing left for me is, if you just say “ydy”, I feel like I am missing something / not understanding something from your explanation - with this one short word, where is the “He” and where is the “has”? Thank you!
The single word “ydy” as an answer automatically contains the gender and the tense of the question.
Yw e wedi mynd? = Has he gone? - answer: He has = Ydy
Yw hi’n barod? = Is she ready? - answer: She is = Ydy
(note for those doing the Northern course - those same questions would be “Ydy o wedi mynd?” and “Ydy hi’n barod?”)
More than slightly off topic, but…
When I was first learning Welsh I was listening to the gorgeous Cerys Matthews being interviewed on Radio 4, and the interviewer asking her how to say “yes” in Welsh. To which she answered, in her lovely sexy voice “there are many ways to say ‘yes’ in Welsh”! Somehow sounded very suggestive…