第3题: [单项选择]The scientist has made quite a few discoveries, ______ of great importance to the whole world. A. which I think they are B. which I think are C. I think which are D. that I think they are 参考答案:B 答案解析:语法结构题。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