fluctuate between (something) and (something)
To move or shift between two things. Would you leave the thermostat alone? The temperature in here is only fluctuating between 70 and 72 anyway.
fluctuate between (someone and someone else)
to waver between choosing one person and another. I am fluctuating between Sam and Tony as my choice. The manager fluctuated between Mary and Sarah as the new assistant.
fluctuate between (something and something else)
to move between one thing and another; to change from one thing to another. Things seemed to fluctuate between the very good and the very bad. The temperature in here fluctuates between too hot and too cold.