now or never

• 立刻, 马上行动起来, 机不可失, 机会难得

now or never的用法和样例：

例句

1. If it was a case of now or never I'd understand you driving over even in this fog.
   如果这是天赐良机，我也就理解你为什么会在这样的雾天里开车外出了。
2. You've got to ask her. It's now or never.
   你得去问她.
3. I felt it was now or never and went right up to him.
   我感到机不可失，所以径直走到他面前。