to be involved in doing something: bị dính líu, bị liên quan hoặc được tham gia làm việc gì đó.

We've caught so many people cheating that we become convinced everyone is at it.

Our street was buzzing with home-improvement activities. Everybody seemed to be at it - painting, gardening, hammering, drilling.

The band has been at it for over a decade without major success.

The group should appeal to new knitters as well as those who've been at it for years.