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 it D. I think is
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 it D. I think is
A
选项中的 I think 是插入语,若略去不看便可清楚地看出答案。