if someone or something moves back and forth between two places, they move from one place to the other place again and again.

Nurses went back and forth among the wounded, bringing food and medicine.

• have coming out ears
• have coming out of ears
• have coming out of your ears
• have coming out your ears
• have day in court
• have dead to rights
• have designs on
• have designs on someone
• have designs on something
• have dibs on
• have dibs on something
• have done more something than has had hot dinners
• have done more something than someone has had hot dinners
• have done more than has had hot dinners
• have done more than someone has had hot dinners
• have [done/seen/had etc.] more something than has had hot dinners
• have [done/seen/had etc.] more something than someone has had hot dinners
• have [done/seen/had etc.] more than has had hot dinners
• have [done/seen/had etc.] more than someone has had hot dinners
• have down on like a ton of bricks
• have down on you like a ton of bricks
• have down pat
• have down to a fine art
• have down to a science
• have ducks in a row