Opportunity knocks but once.

良机难再。

《新英汉大辞典》

Dad often says that opportunity knocks only once, so one must take it when it comes.

爸爸总说机不可失、时不再来，有了机会一定要把握住。

youdao

Opportunity knocks only once.

机会只有一次。

youdao

You May not Get Another Chance - Sometimes opportunity only knocks once.

你也许没有第二次机会——有的机会只会降临一次。

youdao

We believe in the old saying, "Opportunity knocks but just once," so we always welcome it and devote all our spirit and efforts to it.

我们相信，在这个古老的谚语说：“机不可失，但只有一次”，所以我们一直欢迎它，把我们所有的精神和努力。

youdao

Sometimes, an opportunity only knocks at the door once, and if you don't answer it at that particular moment, then you'll never get another chance.

有时，机会只光顾一次。如果你不在那一刻抓住它的话，那么可能你永远也不会再有另一次机会了。

youdao

Of course I wont't chill out. Opportunity knocks only once.

我当然不会罢手的，机会难得嘛。

youdao

Opportunity knocks but once, so we must make the most of it.

机不可失，失不再来，所以一定要把握时机。

youdao

Opportunity knocks but once, so we must make the most of it.

机不可失，失不再来，所以一定要把握时机。

youdao