【题目】I visited Mr. Johnson during his stay in Shanghai he attended a most important conference there.
A.when B.which C.where D.in which
在线课程【答案】 A
【解析】
试题分析：考察定语从句引导词。该句是一个when引导的定语从句，先行词是前面during his stay in Shanghai，when在句子中做时间状语。该句意思为：我在约翰逊先生停留在上海参加一个极重要的会议的期间拜访了他。故选A