alternates

n.someone who takes the place of another person

同义词：surrogatereplacement

v.

go back and forth; swing back and forth between two states or conditions

同义词：jump

exchange people temporarily to fulfill certain jobs and functions

be an understudy or alternate for a role

同义词：understudy

reverse (a direction, attitude, or course of action)

同义词：interchangetackswitchflipflip-flop

do something in turns

同义词：take turns

1. The alternates in the competition were ready to step in if needed.
   比赛中的替补选手已经准备好在需要时替换上场。
2. The team alternates between defense and attack strategies during the game.
   在比赛中，队伍在防守和进攻策略之间交替进行。
3.