问题补充：
Is this research center you met some foreign guests last week?
A. that
B. where
C. which
D. in which
答案：
A. that
(答案→)B. where
C. which
D. in which
解析：考查表语从句。本句是一个一般疑问句，陈述语序是This research center is where you met some foreign guests last week.。where引导的是一个表语从句，where在句中做状语。特别注意D选项，因为缺少先行词所以D错误。结合句意可知B正确。句意：这家研究中心是不是上星期你遇见一些外国客人的地方？
