Ceacht 18:
i	in	prep.	
an raibh sé?	was he, it?	[interr.part.]+[ dep. form (past tense) irreg. v.]+[pron.]	
an raibh siad?	were they?	"	
i mbus	in a bus	[prep.]+[n m4  #ecl.#]	
i dtraein	in a train	[prep.]+[n f5  #ecl.#]	
i mbád	in a boat	[prep.]+[n m1  #ecl.#]	
i long	in a ship	[prep.]+[n f]	
in eitleán	in a aeroplane	[prep.]+[n m1]	
i gcarr	in a car	[prep.]+[n m1  #ecl.#]	
riamh	ever, never	adv.	
aréir	last night	adv.	
cinnte	surely, certainly	adj.	
cúpla	a couple/ twins	n m4	
cúpla duine eile	a couple of others	[n m4]+
[n m4]+[deter.]	
aon duine eile	any other person	[n m1]+ [n 4] +[deter.]	
mar	because	conj.	
freisin	also	adv.	
seo an t-arán	here's the bread	[pron.] + [art.] [ n m1]	
ann	there	adv.	

i / in (in). 
i causes eclipsis to nouns beginning with a consonant.
in is used before a noun beginning with a vowel and before a few other words.

cúpla (couple / few).  The singular noun is used following cúpla, even though we're talking / writing about more than one item.