wiseacre

noun

1. 自以为无所不知的人；自以为是的人
   a person who is annoying because they are very confident and think they know a lot

1. Such sayings themselves grow harder and adhere more firmly with age, and it would take many blows with a trowel to clean an old wiseacre of them.
   这种话的本身也愈经久而愈牢固了，必需用瓦刀一再猛击之，才能粉碎它，使一个自作聪明的老人不再说这种话。
2. Allen is a wiseacre who hears the grass grow.
   艾伦是个自作聪明的人，对什么事都非常敏感。

noun

1. an upstart who makes conceited, sardonic, insolent comments

   Synonym:    wise guysmart aleckwisenheimerweisenheimer