V with n
II.18 The 'catch up' group
These verbs are concerned with reaching or remaining at a particular level or position. The prepositional phrase indicates who you are following, or what topic or action is involved. We include here fall behind, which indicates that someone fails to remain at a particular level.
catch up fall behind keep up
If children are removed from their poor environments, they can catch up with other children.
Hard-pressed homeowners can soon expect even tougher action from banks and building societies if they fall behind with mortgage repayments.