问题补充:
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 which is
答案:
(答案→)A. which I think is
B. which I think it is
C. which I think it
D. I think which is
解析:考查定语从句。句中I think为插入语,先行词为discovery,在定语从句中作主语,故选A。句意:他又有一个杰出的发现,对科学有很大的作用。