To harbor sinister intentions; to have vicious motives or evil designs.
那个商人表面上和蔼可亲，实际上居心险恶，常常设计欺骗那些毫无防备的顾客。
The merchant appeared kind and approachable on the surface, but in reality, he harbored sinister intentions, often devising schemes to deceive unsuspecting customers.
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