问题
选择题
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
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。