So, since it seems people are confused about Verbal Nouns, I'm going to try and explain them, and their uses, here.
Bold is going to be used for incorrect forms, whereas italics will be used for all Irish stuff and (English translations will be in parentheses)
So the verbal noun generally has two main uses: as the present continuous (English -ing) and as an infinitive (English to ___). To form each of these, you use them in different ways.
So to form the gerund, you use ag followed by the verbal noun. Tá mé ag ithe (I am eating)
Now, if there verbal noun in this case has an object, that object is put in the genitive case. Tá mé ag ithe éisc (I am eating a fish).
However, if this object is a pronoun, it cannot be at the end. Instead, ag changes to do, and then it is followed by the possessive pronoun corresponding to the original pronoun, with the appropriate mutation. You also need to remember do + a is á (written dhá in some dialects), and do + ár is dár. Note: in some dialects, it remains ag and doesn't change to do.
Tá mé ag ithe iad will instead be Tá mé á n-ithe (remember a meaning "theirs" eclipses). This can also be used to refer to the subject as well, but you must add the reflexive pronoun. Tá sé á bhualadh féin (He is hitting himself)
However, if you have your object fronted (for emphasis, possibly) or you use a question word that responds to the object (What are you saying?/ You are saying what?), you will not use ag. Instead, you would use something similar to the infinitive, explained below.
Céard atá tú a rá? (What are you saying?)
Note: for this latter construction, Duolingo often gives you a passive one instead, yet translates it as active. Céard atá á rá agat is not active, and is better translated as "What is being said by you?"
The other main use is as the infinitive. This is the form you will see after phrases like Is maith liom, etc. To form it, without an object, you just use the verbal noun. Is maith liom ithe (I like to eat).
If this one has an object, the object goes in the front, you add the particle a and lenite if possible. Is maith liom bia a ithe To negate this, you use gan in front of the object. Tá mé sásta gan míle a shiúl (I am happy not to walk a mile)
It can also be used for other things, such as the passive (which Duolingo uses a lot, though it translates it as active), and can be used with certain other words to convey intention/purpose/duty (le), "going to" (chun), "just after" (the origin of the Hiberno-English "I'm after ...") (tar éis), something that isn't done (gan), and the status following an action (ar). I won't go into any of these until asked, as it can get complicated.
If you have any questions, please ask me and I'll try and make things clearer!
you have 'is maith liom ithe' for i like to swim :p
EDIT: i forgot to see a massive thanks!!
Oops! Originally had Is maith liom snámh, but changed it to better contrast with the following example.
ya i really think Team Irish should use most of this to add to their tips and notes if you were ok with it :)
oh and p.s. are you from galway? me too!
Actually, nah. I'm from America, and have no connection to Ireland (well, that isn't distant). I was just in Galway my first time there and fell in love (plus, my main and most influential Irish teacher is from there).
And glad it makes sense. If there's any other topics you're confused about, I can make a post about them as well.
Your English “-ing” examples are present participles rather than gerunds; for example, “I am eating” uses the present participle “eating”, but “I like eating” uses the gerund “eating”.
That's my bad. Guess that's what happens when they all have the same form! Actually, looking again, I can't find anything about Irish having a gerund.
Irish doesn’t have gerunds; Irish has verbal nouns, and among their uses is to translate English gerunds, e.g. “Eating is good.“ → Tá ithe go maith.