1. Act of God 天意，不可抗力

He is successful at last. It may be an act of God. 他终于成功了，这也许是天意。

释义：直译是上帝的行动，而上帝的行动是不可预计的，所以比喻无法预计，难以避免的事情。

2. Act up 胡闹，出毛病

The children started to act up as soon as the teacher left the classroom. 老师一走，孩子们就闹起来了。