When to use [verb] + ais i or Gwnes i + [verb]

[ChrisPrice]

I know there are two main ways of conjugating verbs in the past tense- ‘coginiais i’ or ‘gwnes i goginio’. Are there any particular rules that apply to when either form is used? I’ve noticed SSiW so far prefers ‘wnes i’ and ‘wnest ti’ and I wanted to know if this is a preference thing or a grammar thing.

I’m not too far into the SSiW course, so I’m not sure if it comes up later but I wanted to ask about this anyway as I find it quite confusing.

Diolch am ddarllen ac am unrhyw atebion!

[Hendrik]

@ChrisPrice

I know there are two main ways of conjugating verbs in the past tense- ‘coginiais i’ or ‘gwnes i goginio’. Are there any particular rules that apply to when either form is used?

There is no difference in meaning between the two, and you’ll mostly hear the “short form” for the “big” irregular verbs like mynd, dod and cael, and for a few short everyday verbs like dweud and gweld. The auxiliary form is more likely to be seen in longer, rarer, verbs, but there are no set rules. Ultimately it’s a question of speaker’s preference.