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.