fire something off

Từ điển Oxford Advanced Learner 8th

ˌfire sthˈoff derived
1. to shoot a bullet from a gun
•They fired off a volley of shots.
2. to write or say sth to sb very quickly, often when you are angry
•He fired off a letter of complaint.
•She spent an hour firing off emails to all concerned.
Main entry: ↑fire_derived