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

1.
遅れる, 遅れをとる
to fail to make enough progress or to be late with something
:
•
I've got behind with my work.
仕事が遅れています。
•
If you miss a few classes, you'll soon get behind.
数回授業を休むと、すぐに遅れてしまいます。
遅れる, 遅れをとる
to fail to make enough progress or to be late with something