Opportunity knocks but once.

机会只来一次。

Opportunity knocks only once, but temptation bangs on your door for years.

机会是只有一次，但诱惑却在无时不刻地捶打着你的门。

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。

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。