Witnesses say the firing was deliberate and sustained.
目击者说这次射击是蓄意的，而且还持续了一段时间。
《柯林斯英汉双解大词典》
2
A hand-driven machine gun, the Gatling gun was the first firearm to solve the problems of loading, reliability, and the firing of sustained bursts.
早期的盖特机炮虽然要靠手摇才能开火，但它毕竟是同时解决了装弹、稳定性、连续开火问题的首款火力武器。
3
Repetitive firing can be induced by a sustained depolarizing stimulation in DRG neurons with frequency proportional to the intensity of depolarization.