"You are not busy, I am busy!"
Translation:Chan eil thu trang, tha mise trang!
They are entirely different to be verbs and they serve different purposes.
One – the substantive verb bi with forms such as tha and (bh)eil – is used to describe things and people and their whereabouts but not to classify/define them nor to identify them – state what or who they are.
The other one – the copula is – is mostly used to identify and classify – stating who or what sth or somebody is (but it has many other usages and it also might be used to describe things or people, especially in poetic language).
I’ve described the difference multiple times in the discussions, look especially at the "It is another sandwich" sentence discussion and the second part of my post in the Tha ... ann thread, you may also read the Introduction question thread about is mise.
For those on the app, Silmeth is now keeping a blog on this topic here: https://www.celtic-languages.org/Guide_to_Scottish_Gaelic_to_be
However the "it is another sandwich" link is here: https://forum.duolingo.com/comment/45459577
And the "Tha ... ann" thread is here: https://forum.duolingo.com/comment/38688604?comment_id=38716029
And the "Introduction question" thread about is mise is here: https://forum.duolingo.com/comment/35387474
(Sadly, markdown has been broken for some time on the app version of Duolingo, so links and most other formatting using markdown won't work or will have weird results in the app; Duolingo doesn't seem interested in fixing it.)
I've read the posts above, and the links. They are very informative, but I am wondering about the "mise". If the sentence was "I am not busy, you are busy!", would it be "Chan eil mi trang, tha thusa trang!"? What is the difference between the two phrases? Thank you for your patience. * Aha! I just needed to be patient. Farther in the skill my question was answered. (and then I read the tips more carefully). I see that "Tha mise trang!" is being emphatic about the comparison. Mise is more empatic than mi. A two year old would use this word if we had such a thing in English. * Thanks, all!!