Have a good one. 再见.

这句话和Have a good bay.及Have a nice day.意义相同.

但是 Have a good one 中的 one 是指 day.morning.afternoon.evening. 或 night.

所以在任何时候和别人道别的时候.都可以说 Have a good one.

早上再见的时候.可以说：Have a good morning.

下午再见的时候.可以说：Have a good afternoon.

晚上再见的时候.可以说：Have a good evening.

或 Have a good night.

但是任何时候都可以说：Have a good one.