"Yes, I have gone to work."

Translation: Ydw, dw i wedi mynd i'r gwaith.

[TARDISInSpace]

Is there an explanation/ rule for it being 'to the work' in Welsh rather than 'to work'?

[EllisVaughan]

We use "i'r" when we talk about a place we gi to habitually e.g work or school.

[mizinamo]

I think you'd have to provide an explanation for why English doesn't say "to the work"... we don't say "I went to supermarket" or "I went to doctor" or even "I went to office", after all.

So Welsh (and German) simply is more consistent here and uses "the" even for places that you go to habitually and/or for their intended purpose.

[silverlight513]

Are other variations of yes allowed, such as ye or oes? Everyone I know who has been brought up fluent just use ye for everything.

[EllisVaughan]

Technically using Ie/Ia for everything is incorrect, so it is better for the course to teach the proper forms of yes. Oes is only used to answer oes questions.