fall behind with
phrasal verbfall behind with something
(also fall behind on something especially in North American English)
- to not pay or do something at the right time
拖欠（付款）；没有及时做 - They had fallen behind on their mortgage repayments.
他们拖欠了按揭还款。 - He's fallen behind with his school work again.
他又没有按时做学校作业。
- They had fallen behind on their mortgage repayments.