slack in the screw

例句：

1. 3.
   在工作、学习等中
2. 1. The team is slacking off on their training.
   团队在训练时松懈了。
3. 2. The car's engine is slacking out.
   汽车的引擎动力不足。
4. 3. She slacked off on her studies recently.
   她最近对学习松懈了。