on the fly
1．in flight在空中；在飞行中
*Tom was called out because the catcher caught the ball on the fly．汤姆被判出局,因为接球员接住了飞来的球.
2．busy忙碌
*Getting the house ready for the visitors kept Mother on the fly all day．为了把房子整理好接待客人,母亲忙碌了一整天.
*The housekeeper of our school is always on the fly．学校管理员整天忙得很.
根据语境就是匆忙 马马虎虎的意思