Doctor Smith has made another wonderful discovery, great importance.
A. which I think is of
B. which I think it is of
C. which is I think
D. I think which is
网友回答
(答案→)A. which I think is of
B. which I think it is of
C. which is I think
D. I think which is
解析：句意：斯密斯博士做出另外一个发现，这我认为是很重要的。这里使用了非限制性定语从句，修饰discovery，which在定语从句中做主语，I think是插入语，选A。