【题目】Common sense requires us to get away from the concept that national boundaries are frontiers _________ knowledge may not spread.
A. with which B. across with
C. through which D. from which
在线课程【答案】B
【解析】
试题分析：考查定语从句。句意：常识需要我们摆脱一些传统观念，那就是国界就是知识通过它不可能传播的国界。spread across通过---传播。故选B。