单选题 The professors suggest that the essence of principled negotiation is to separate the person from the problem and on focus on interests, and not to position.

A、 abstract
B、 core
C、 subtract
D、 idea

【正确答案】 B

【答案解析】abstract：提要，抽象；core：核心，精髓；subtract：扣除，减损；idea：主意，念头。题中essence意为“实质，要素”，故选B。