Verb
One
I’m = ime – είμαι.
You are = ise – είσαι.
He/she/it is = ine – είναι.
Plural
We are = imaste – είμαστε.
You are = isaste or iste – είσαστε η είστε.
They are = ine – είναι (third person is the same in one or plural).
p.s
When you speak with someone that you don’t know well, it’s better to speak to him/her in plural (except when you speak about yourself). Plural is the gentle way to speak with someone you don’t know, but if you know him/her it’s not right because you put distance between you and him/her.