adj.秘密的，阴险的，狡诈的，卑鄙的

He was accused of underhand dealings to win the contract.
他被指控采取不正当手段赢得了合同。
She tried to play an underhand trick on her opponent in the game.
她在比赛中试图对对手耍诈。
The politician's underhand campaign tactics caused public outrage.
那位政客的不正当竞选策略引起了公众的愤怒。
Don't try to deceive me with underhand means; it won't work.
不要试图用狡猾的手段欺骗我，那不会奏效。
The teacher caught the student passing notes underhand during class.
老师发现学生在课堂上偷偷传递小纸条。
Underhand copying is a violation of copyright law.
私自复制是侵犯版权的行为。
He played an underhand role in the business, avoiding direct responsibility.
他在生意中扮演着不光彩的角色，逃避直接责任。
In chess, an underhand move can lead to a quick defeat.
在国际象棋中，不正当的一步可能导致迅速落败。
She disclosed the underhand plot to her superior, leading to its exposure.
她向上司揭露了这个阴谋，导致其曝光。
His underhand behavior towards his colleagues created a toxic work environment.
他对同事的不正当行为营造了一种恶劣的工作氛围。