"He is going to chapel tomorrow."
Translation:Mae e'n mynd i'r capel yfory.
Why is it both e'n and o'n? Sire i've o ly ever seen e'n before in the exercises?
o/fo is just a dialect variant of e/fe often used in the day-to-day language in north and parts of mid-Wales.
This is explained in various parts of the course notes.
Why is it i'r and not just i when the translation doesn't include "the"? Is that a Welsh thing to do?
This is explained in the notes for the section. English and Welsh language patterns are often quite different from one another, and this is an example.
i'r.. is used for places that we attend regularly:
- *Dw in mynd i'r gwely/capel/ysgol/gampfa/swyddfa/eglwys...
On the website, each skill (e.g. https://www.duolingo.com/skill/cy/Greeting1 ) has a list of lessons at the top and usually a list of "Tips and notes" for that skill below the lessons.
Tips and notes are not (yet) available in mobile apps -- a grave disadvantage of the apps in learning a language, in my opinion.
If you're using an app, you may want to consider switching to using the website instead, at least for learning new skills rather than practising ones you have already seen before.
From what I've heard, it's best to access the website from a laptop/PC/Mac or at least a tablet in landscape mode -- if website notices that the screen it's being displayed on is too small, the website will change its design to something resembling the mobile app and will not display the tips and notes either.
Yes, it's hard to explain a language just by presenting example sentences.
The Welsh team have done a great job in supplementing the sentences with grammar notes, so it's always a shame when mobile users aren't aware of them because the app doesn't tell them about the availability of grammar notes on the website.
It does make things a lot clearer if you get to read those explanations before starting a new lesson!