
Before you know it=something's happened very very quickly while you won't pay attention. 在你不知不覺中。
例句 One day your daughter's crawling around in diapers,before you know it she's dating a guy driving a motorcycle.
那時候你女兒還在尿布上爬呢,不知不覺地,她現在都能跟騎摩托的小伙子約會了。
If you start saving now,before you know it,you'll have enough money for college.
如果你現在開始攢錢,不知不覺中,你就能供自己上大學了。