that will be the day

1. My husband, get up before eight o'clock?That will be the day!
要我丈夫八点以前起床吗?那样的事永远不会发生!

来自《简明英汉词典》

2. It is not uncommon that a sunny morning will turn out to be a cloudy day at this time of the year.
一个晴朗的早晨变成阴天,每年这个时候都并不少见。

来自《简明英汉词典》