问题补充：
Some people are bad at recalling names and faces, so its possible that they have a condition called face blindness, people suddenly have trouble recognizing family members, friends or even themselves．
A. for which
B. which
C. where
D. of which
答案：
A. for which
B. which
(答案→)C. where
D. of which
解析：考查从句，从句people suddenly have trouble recognizing family members, friends or even themselves句子不缺少成份，所以选where，句子意思“有些人不善于回忆名字和脸，这有可能是连忙正，那里的人们突然在认识家人、朋友和自己有困难”，所以选C
