16. He made another wonderful discovery of great importance to science.A. I think which

问题补充：

16. He made another wonderful discovery, of great importance to science.

A. I think which is

B. which I think it is

C. which I think it

D. which I think is

答案：

A. I think which is

B. which I think it is

C. which I think it

(答案→)D. which I think is

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