那个赌场常客其实是个老练的赌场骗子，专门在扑克牌上做手脚。

The regular at the casino turned out to be a skilled ___card-sharp who manipulated the poker games.

那个看起来无害的老人其实是个老练的赌牌高手。

The harmless-looking old man turned out to be a skilled ___card-sharp.