many a slip between the cup and the lip字面意思在杯子和嘴唇之间还会有许多失误，引申为事情往往功败垂成。

【例句】
There’s many a slip between the cup and the lip! Who knows what may happen.
事情往往功敗垂成， 谁知道将会发生什么。

Well, there is many a slip between the cup and the lip!
哦，凡事总难避免意外发生的。