let off

动词 let off:

1. grant exemption or release to
   同义词：excuse, relieve, exempt

1. The janitor let off some steam because the pressure was too high.
   由于压力过高，火炉工放掉了一些蒸气。
2. The boys were letting off fireworks.
   男孩子在放烟火。
3. We've been let off school today because our teacher is ill.
   今天学校放假，因为我们的老师病了。
4. She was let off with a fine instead of being sent to prison.
   没让她入狱，而是罚款了事。