N3 — outside your level filter
Is said whole, with nothing composed onto it and takes no だ／です, so there are no forms to conjugate.
くせがつく
kusegatsukufall into a habitN3expression
Example sentences1
くせがつく前に、直した方がいいよ。
kuse ga tsuku mae ni, naoshita hou ga ii yo.
You'd better fix it before the habit sets in, you know. casual