There are two ways of saying should or ought to (which are treated as conceptually the same) in Welsh, using dylwn (south) and dylswn (north). It’s best to be aware of both, and let local usage dictate which one you use.
Do not use yn , and following verbnouns such as coginio , to cook , will take soft mutation in the affirmative and interrogative, but do not mutate after dim . Dylwn is sometimes used with the affirmative particle fe which causes soft mutation.
Affirmative
English Welsh Alternative Examples I should, I ought to dylwn i fe ddylwn i dylwn i goginio you should, you ought to dylet ti fe ddylet ti dylet ti goginio he should, he ought to dylai fe fe ddylai fe dylai fe goginio she should, she ought to dylai hi fe ddylai hi dylai hi goginio Carys should, Carys ought to dylai Carys fe ddylai Carys dylai Carys goginio the girls should, the girls ought to dylai’r merched fe ddylai’r merched dylai’r merched goginio we should, we ought to dylen ni fe ddylen ni dylen ni goginio you should, you ought to dylech chi fe ddylech chi dylech chi goginio they should, they ought to dylen nhw fe ddylen nhw dylen nhw goginio
Interrogative
English Welsh Alternative Examples should I? ought I? ddylwn i? – ddylwn i goginio? should you? ought you? ddylet ti? – ddylet ti goginio? should he? ought he? ddylai fe? – ddylai fe goginio? should she? ought she? ddylai hi? – ddylai hi goginio? should Carys? ought Carys? ddylai Carys? – ddylai Carys goginio? should the girls? ought the girls? ddylai’r merched? – ddylai’r merched goginio? should we? ought we? ddylen ni? – ddylen ni goginio? should you? ought you? ddylech chi? – ddylech chi goginio? should they? ought they? ddylen nhw? – ddylen nhw goginio?
Negative
English Welsh Alternative Examples I should not, I ought not ddylwn i ddim – ddylwn i ddim coginio you should not, you ought not ddylet ti ddim – ddylet ti ddim coginio he should not, he ought not ddylai fe ddim – ddylai fe ddim coginio she should not, she ought not ddylai hi ddim – ddylai hi ddim coginio Carys should not, Carys ought not ddylai Carys ddim – ddylai Carys ddim coginio the girls should not, the girls ought not ddylai’r merched ddim – ddylai’r merched ddim coginio we should not, we ought not ddylen ni ddim – ddylen ni ddim coginio you should not, you ought not ddylech chi ddim – ddylech chi ddim coginio they should not, they ought not ddylen nhw ddim – ddylen nhw ddim coginio