Do you understand me?

A bheil thu gam thuigsinn? 

Until now we have used simple sentences with verbal nouns the –ing words, like dèanamh (doing), and tuigsinn (understanding). But if we want to say, for example, are you understanding me , we would not say a bheil thu a' tuigsinn mi . That is an absolute no-no!  

If we want to use a pronoun , that is to say mi, thu, e, i, sinn, sibh, iad as the object of a verbal noun , we use a prepositional possessive . We combine the preposition aig (at) with a possessive adjective such as mo (my). The Gaelic for 'understanding me' , becomes ‘ gam thuigsinn' , literally ‘at my understanding’. 

And to say 'I’m doing it'? Not a’ dèanamh e but ga dhèanamh!  

Preposition Prepositional Possessive Lenites? 
aig + mo =  gam  at my Yes 
aig + do =  gad  at your Yes 
aig + a =  ga  at his Yes 
aig + a/a h- =  ga/ga h - (before vowels) at her No 
aig + ar/ar n- =  gar  at our No 
aig + ur/ur n- =  gur / gur n- (before vowels) at your (pl) No 
aig + an/am =  gan / gam (before b, f, m, p ) at their No 
aig + mo
at my
aig + do
at your
aig + a
at his
aig + a/a h
at her
aig + ar/ar n
at our
aig + ur/ur n-
at your
aig + an/am
at their
gam
at my
gad
at your
ga
at his
ga/ga h-
at her
gar
at our
gur/gur n-
at your
gan/gam
at their