back and forth
US /bæk ən fɔːrθ/
UK /bæk ən fɔːrθ/

1.
heen en weer
moving first in one direction and then in the opposite direction repeatedly
:
•
The pendulum swung back and forth.
De slinger zwaaide heen en weer.
•
They walked back and forth across the room.
Ze liepen heen en weer door de kamer.
2.
heen en weer, tussen twee punten
between two points, people, or places
:
•
The ball went back and forth between the players.
De bal ging heen en weer tussen de spelers.
•
They exchanged emails back and forth for days.
Ze wisselden dagenlang e-mails heen en weer uit.