Ceacht 19:
ann	there	adv.	
nach raibh sé?	wasn't he?	[neg. interr.part.]+[ dep. form (past tense) irreg. v. 'bí']+[pron.]	
cá raibh sí?	where was she?	[inter adv]+[ dep. form (past tense) irreg. v. 'bí']+[pron.]	
an cat	the cat	[def. art.]+[n. m1]	
an madra	the dog	[def. art.]+[n. m4]	
an bhó	the cow	[def. art.]+[n. f4  #len.#]	
an capall	the horse	[def. art.]+[n. m1]	
an t-asal	the donkey	[def. art.]+[n. m1  #prefix#]	
an chaora	the sheep	[def. art.]+[n. f5  #len.#]	
an-fhada	very long	[adj.  #len.#]	
i bhfad	a long time	prepositional phrase [i] + [adv  #ecl.#]	
a lán daoine	many people	[part.] + [adj.] + [n m4]	
cúpla nóiméad	a couple of minutes	[n m4] + [ n. m1]	
ag fanacht leat	waiting for you	“ag” + [vn] + [prep. pron.]	
ag súgradh	playing	“ag” + [vn]	

go (that):  In this lesson we see a phrase "bhí a fhios agam go raibh" which translates as "I knew that (somebody / something) was".  The little word (or conjunction to give it its proper name) "that" in the English sentence can often be omitted without altering the meaning of the sentence, but it is an essential element in the Irish sentence.

We could re-write the English sentence as, for example, "I know you were in the shop" and it still makes sense.  In Irish, this would be translated as "Bhí a fhios agam go raibh tú sa siopa" but we must use the conjunction go, which is followed by the dependant form of the verb (in this case, raibh)