Intermediate lesson 23 "roedd dy rhai di" or "roeddan eich rhai chi"

In lesson 23 of the intermediate course (about 21 minutes into the lesson) I had thought that “Your ones were running very fast” would have been rendered as " roeddan eich rhai chi yn rhedeg fel y diawl" but was surprised that it was actually translated as “Roedd dy rhai di yn rhedeg fel y diawl”. Why singular for “ones”?
Yours, puzzled,
Gerald Murphy

Da iawn - challenge 23 is pretty good going!

The unexpected pattern is just a feature of the Welsh language that doesn’t map onto English. I guess it’s a bit like when you say “four dogs”, and in English you use the plural, dogs, but in Welsh, although there’s four of them, you still use the singular - “pedwar ci”, not “pedwar cŵn”.

If you forget and use the “wrong” form of roedd, it won’t spoil the meaning, although it will sound a bit odd, and be a bit more difficult to say, so don’t worry about it. You’ll soon get used to it and forget that it was ever an issue!

Thanks Iestyn. I realised after I posted the question that the “eich…chi” bit was also a false assumption since it could have been one person who was being addressed. Anyway, your answer has clearedup my main question.

Another thing which might be confusing the issue is this: the “they” verb forms are only ever used with the actual word for “they”, and not with other equivalent plural thingies.

So in most languages, to say “they were” or e.g. “the cats were”, you’d use the same word for “were” in each case.

But in Welsh it’s a bit different. If you want to say “they were”, it’s roeddan nhw. But to say “the cats were”, even though “the cats” is a “they”-type thing, it’s actually roedd y cathod - not *roeddan y cathod as you might expect.

(In case anyone wants that in grammatical terms - 3rd-person plural verb forms are only used with the 3rd-person plural pronoun nhw; other 3rd-person plural subjects take the 3rd-person singular verb form.)

Thank you so much. That really has made it much clearer to understand why.