trigger
/ˈtrɪgə(r); `trɪɡɚ/ n
lever that releases a spring, esp so as to fire a gun （释放弹簧的）扳柄; （尤指枪的）扳机
squeeze the trigger 扣扳机
have one's finger on the trigger, ie be ready to shoot 手指触及扳机（准备射击）. =>illus at gun 见 gun 插图. trigger, v [Tn, Tn.p]
~ sth (off) be the cause of a sudden (often) violent reaction; set an action or a process in motion 成为突然发生的（常为激烈的）反应的原因; 发动; 引发
The riots were triggered (off) by a series of police arrests. 警方一连串的逮捕行动激发了暴乱.
The smoke triggered off the alarm. 这些烟把警报器触响了.