The overseas Chinese scientist made another wonderful discovery, of great value to study AIDS.
A. which I think it is
B. which I think is
C. I think it is
D. I think is
网友回答
A. which I think it is
(答案→)B. which I think is
C. I think it is
D. I think is
解析：考查定语从句：先行词是discovery，定语从句中I think是插入语，定语从句中which做主语，it是多余的，句意：海外的中国科学家做出另一项重大发现，我认为这对研究艾滋病很有价值。选B。