Should it be they always very busy or they're always very busy? Which one is it,

Should it be they always very busy or they're always very busy? Which one is it,

they're always very buzy.
To be a sentence, you must have a verb
Here they're is the abbreviation of they are
They are the subject of the whole sentence
Are is a copula, which means they are often busy
If there is no "are" in the sentence, there must be a "do" verb
For example: they always lie