Question

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

Answer 1

B

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。