get behind
US /ɡet bɪˈhaɪnd/
UK /ɡet bɪˈhaɪnd/

1.
뒤쳐지다, 늦어지다
to fail to make enough progress or to be late with something
:
•
I've got behind with my work.
나는 내 일에 뒤쳐졌다.
•
If you miss a few classes, you'll soon get behind.
몇 번 수업을 빠지면 금방 뒤쳐질 거야.