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
解析:可联系答.案.网客服索取。