2017考博英语完形填空逻辑关系类词汇：对比与时间
考博英语完形填空解题要点之一即搞清楚逻辑关系，承上启下。新东方在线考博频道总结了十大重要逻辑关系类词汇，希望考生能够认真理解和把握，争取攻克完形填空难关。
对比关系词: while; whereas ; as; instead of; rather than; not…but;
时间关系词: when; whenever, before; after; since; as; while; until; till; simultaneously; meanwhile; in the meantime, at the same time;