（四）非限定定语从句对被修饰的名词起附加说明，或进一步描述或补充。

        这种从句有一定的独立性，即使去掉，主句的意思仍然完整，只是内容相对地不够具体。与主句之间常用逗号分开，所用的关系代词与限定性定语从句基本相同，但不能用关系代词that 引导。

        （1）An Old friend from abroad, _____I was expecting to stay with, telephoned me from the airport.

        A. that

        B. whom

        C. who

        D. which

        （答案：B）（2000年31题）

        （2）His brother had become a teacher, _____he wanted to be.

        A. who

        B. what

        C. which

        D. that

        （答案：C。which引导的非限定性定语从句，在从句中做宾语，修饰先行词a teacher）（1997年39题）

        （3）He has made another wonderful discovery, _____of great importance to science.

        A. which I think it is

        B. of which I think it is

        C. I think which is

        D. which I think is

        （答案：D。which引导的非限定性定语从句，修饰前面整个句子。）（1995年50题）

        （五）“名词（代词）+介词+关系代词”引出，一般是非限定性定语从句。

        We’ve tested three hundred types of boot, _____is completely water proof.

        A. no of which

        B. none of which

        C. some of which

        D. neither of which

        （答案：B。“名词（代词）+of+which（whom）”引起的定语从句常表示部分与整体的关系。）（1995年36题）