He made another wonderful discovery, of great importance to science.
A. which I think is
B. which I think it
C. which I think it is
D. I think which is
网友回答
(答案→)A. which I think is
B. which I think it
C. which I think it is
D. I think which is
解析：
试题分析:考查定语从句。根据结构可知逗号后面是定语从句，从句中I think是插入语，which是关系代词做主语，由此可知A选项正确。 句意：他又有了一个奇妙的发现，我认为这对科学界很重要。