When does it become "leat" and when is it "leabh"
How do you know when to put the 'a' in and when not to please?
Use a in front of a consonant and leave it out in front of a vowel.
Leat is informal, leibh is formal so used for showing respect to. I think this is the case anyway.
Singular and informal, sibh is plural, and also used for singular but formal. Pretty standard T-V distinction, which even English used to have (thee/thou & you/ye).
What's the difference between "Mar sin" and "Slán"? is this last one more informal?
What is the literal translation of "Mar sin leat"?