1、轮流
...take pains to do 努力做某事take turn 轮流take up 占据(时间，地方)，从事于 ...
2、当值
直 ... 遇,碰上 [meet] 当值,轮值,轮班[take turn;in turn] 担任 [undertake;assume the office of] ...
3、依次轮流
...cut hair 理发take turn 依次轮流in the barber’s chair 坐在理发店的椅子上 ...
4、依次
... take the place of 代替，取代 take turn 依次，轮流 throw light on 阐明，使…了解 ...