问题补充：
It seems that this medicine has a good effect on the patient, he may die in great pain.
A. when
B. where
C. by which
D. without which
答案：
A. when
B. where
C. by which
(答案→)D. without which
解析：考查定语从句中的介词。定语从句中关系代词前面的介词有三种来源：先行词的搭配；定语从句中词汇到的搭配；句子上下文的意思；本题根据句意说明使用without;句意：似乎这种药对病人有好的效果，要是没有药，他会死于痛苦。根据句意说明使用without.
