"I am going to the beach Sunday."
Translation:Dw i'n mynd i'r traeth dydd Sul.
Strictly speaking if we're talking about 'On' Sunday, it should be 'ddydd Sul' which is a contraction of ar ddydd Sul (On Sunday)
But in general speech it is very hard to differentiate between them so for the sake of simplicity in the earlier parts of the course the non-mutated form is used.
It should be ddydd Sul because it is an adverb of time - it says when we will do something - and these are generally mutated in Welsh:
- Es i yno ddoe - I went there yesterday (ddoe always has that mutation)
- Ro'n ni'n mynd yno weithiau - We used to go there sometimes (weithiau comes from gweithiau)
- Mae hi'n ennill bob tro - She wins every time (bob tro is a soft mutation of pob tro)
- Byddi di yno ddydd Llun - You'll be there on Monday
Yes, rydw i is equivakent to dw i in positive statements. It is just slightly more formal. dw i is the form usually taught on 'Welsh for Adults' courses as it is so widely used. I understand that rydw i is widely taught in schools, though.
Many of the Duo phrases will accept dw i, rydw i, dwi and rwy as answers in positive statements in the present tense even though we only use dw i in the prompts. We have not yet got round to including all four in every instance, though.
There are some other, less common dialect variants and a couple of formal variants that we do not cater for.