问题补充:
He made another wonderful discovery, of great importance to science.
A. which I think it is
B. which I think is
C. which I think
D. I think which is
答案:
A. which I think it is
(答案→)B. which I think is
C. which I think
D. I think which is
解析:考查插入语:句意:他做出了一个重大发现,我认为这对科学是非常重要的,which引导的是非限制性定语从句,I think是插入语,在which后面,去掉I think可知which是定语从句的主语,it是多余的,选B。