in action
US /ɪn ˈækʃən/
UK /ɪn ˈækʃən/

1.
投入使用, 在行动中
doing something or operating, rather than being still or inactive
:
•
It's great to see the new machine in action.
很高兴看到新机器投入使用。
•
The coach likes to see his players in action during practice.
教练喜欢在训练中看到他的球员表现出色。