back ·phrase
Definition: in one direction, then the opposite way, then in the original direction again many times Level: C2
他每周都不得不在伦敦和巴黎之间来回奔波。
He has to travel ___back ___and ___forth between London and Paris every week.
最终，在来回走了很久之后，我们找到了一条路，沿着它走到了镇上。
Finally, after much walking ___back ___and ___forth, we found a road which we followed till we got to the town.
谈判代表在两个房间之间来回穿梭，试图达成妥协。
The negotiators shuttled ___back ___and ___forth between the two rooms, trying to reach a compromise.