i never know what's going to set my daughter off

问题描述:

i never know what's going to set my daughter off

这里 set off 是激起,引起,使发动的意思
我从来不知道什么会让我女儿大笑/让我女儿激动/让我女儿大发脾气.(只能揣摩基本意思)
只有联系上下文,才能最准确的把握句子意思.
set somebody off. to make someone start laughing, crying, or talking about something(朗文词典对这一习语的解释)
让某人开始大笑,大哭,或喋喋不休