问题补充：
单选题Thescientisthasmadequiteafewdiscoveries,______ofgreatimportancetothewholeworld.A.which I think they areB.which I think areC.I think which areD.that I think they are
答案：
B解析此题考查非限定性定语从句。非限定性定语从句不能用关系代词that来引导，因而排除D.项；[C]项语序不对；在以Which开头的[A]、B.项中，关键要识别出插入语“I think”，这样显然[A]项中的they为多余的词，因此B.项为正确
