He made another wonderful discovery, of great importance to science.
A. which I think is
B. which I think it is
C. which I think
D. I think which is
网友回答
(答案→)A. which I think is
B. which I think it is
C. which I think
D. I think which is
解析：考查定语从句。句中I think为插入语，which指代先行词discovery，在从句中作主语。句意：他又有一个极好地发现，对科学有重要的作用。