There are two ways of saying would have in Welsh, using byddwn … wedi (south) and baswn … wedi (north), which is often contracted to just swn … wedi . It’s best to be aware of both, and let local usage dictate which one you use.
As both are forms of bod , these auxiliary verbs both use wedi and following verbnouns such as cwympo , to fall , do not mutate.
Affirmative
English Welsh Alternative Examples I would have byddwn i wedi fe byddwn i wedi byddwn i wedi cwympo you would have byddet ti wedi fe byddet ti wedi byddet ti wedi cwympo he would have byddai fe wedi fe byddai fe wedi byddai fe wedi cwympo she would have byddai hi wedi fe byddai hi wedi byddai hi wedi cwympo Carys would have byddai Carys wedi fe byddai Carys wedi byddai Carys wedi cwympo the girls would have byddai’r merched wedi fe byddai’r merched wedi byddai’r merched wedi cwympo we would have bydden ni wedi fe bydden ni wedi bydden ni wedi cwympo you would have byddech chi wedi fe byddech chi wedi byddech chi wedi cwympo they would have bydden nhw wedi fe bydden nhw wedi bydden nhw wedi cwympo
Interrogative
English Welsh Alternative Examples would I have? fyddwn i wedi? – fyddwn i wedi cwympo? would you have? fyddet ti wedi? – fyddet ti wedi cwympo? would he have? fyddai fe wedi? – fyddai fe wedi cwympo? would she have? fyddai hi wedi? – fyddai hi wedi cwympo? would Carys have? fyddai Carys wedi? – fyddai Carys wedi cwympo? would the girls have? fyddai’r merched wedi? – fyddai’r merched wedi cwympo? would we have? fydden ni wedi? – fydden ni wedi cwympo? would you have? fyddech chi wedi? – fyddech chi wedi cwympo? would they have? fydden nhw wedi? – fydden nhw wedi cwympo?
Negative
English Welsh Alternative Examples I would not have fyddwn i ddim wedi – fyddwn i ddim wedi cwympo you would not have fyddet ti ddim wedi – fyddet ti ddim wedi cwympo he would not have fyddai fe ddim wedi – fyddai fe ddim wedi cwympo she would not have fyddai hi ddim wedi – fyddai hi ddim wedi cwympo Carys would not have fyddai Carys ddim wedi – fyddai Carys ddim wedi cwympo the girls would not have fyddai’r merched ddim wedi – fyddai’r merched ddim wedi cwympo we would not have fydden ni ddim wedi – fydden ni ddim wedi cwympo you would not have fyddech chi ddim wedi – fyddech chi ddim wedi cwympo they would not have fydden nhw ddim wedi – fydden nhw ddim wedi cwympo