alternate between

alternate between (people or things)

To switch between two or more different people or things. We are going to alternate between the lead and the understudy at today's rehearsal. The air conditioner alternates between settings depending on the temperature, so I don't think it will get too cold in here.

See also: alternate, between

Farlex Dictionary of Idioms. © 2015 Farlex, Inc, all rights reserved.

alternate between (someone and someone else)

 and alternate between something and something else

to choose or change between two persons or things alternately. The job will alternate between Gil and Ed. The maid will alternate between the first floor and the second floor.

See also: alternate, between

McGraw-Hill Dictionary of American Idioms and Phrasal Verbs. © 2002 by The McGraw-Hill Companies, Inc.