There's many a slip (between the cup and the lip 或 'twixt cup and lip).
释义
There's many a slip (between the cup and the lip 或 'twixt cup and lip). 〈谚〉杯到嘴边还会失手。(指万事难以十拿九稳，事情往往功败垂成) He seems sure that he will pass the examination, but there's many a slip. 他看来对通过考试很有把握，不过凡事很难有十拿九稳的。