A. whom B. them
C. which D. who
【易错】容易误选 B，用 them 代指 students。
【分析】最佳答案是A，many of whom gained great success in their own field 为非限制性定语从句。假若在many of… 的前面加上连词and，则选答案B。比较以下各题(答案均选A)：
(1) He asked a lot of questions, none of ______ was easy to answer.
A. which B. them
C. what D. that
(2) He asked a lot of questions, and none of ______ was easy to answer.
A. them B. which
C. what D. that
(3) He told me that he had two girl-friends, neither of _______ knew anything about the other.
A. whom B. them
C. which D. who
(4) He told me that he had two girl-friends, and neither of _______ knew anything about the other.
A. them B. whom
C. which D. who
■ He had a lot of friends, only a few of ______ invited to his wedding.
A. whom B. them
C. which D. who
【易错】容易误选 A，认为这是非限制性定语从句。
【分析】最佳答案是B，这不是非限制性定语从句，而是一个独立主格结构，因为空格后的动词 invited 并不是一个完整的谓语，而是一个过去分词。当然，假若在 invited 前加上助动词 were，则是一个非限制性定语从句，答案便应选A。比较：
(1) They put forward a lot of plans at the meeting, none of _______ carried out in their work.
A. which B. them
C. what D. that
答案选B，none of them carried out in their work 是独立主格结构，其中的 carried out 为过去分词。
(2) They put forward a lot of plans at the meeting, none of _______ were carried out in their work.
A. which B. them
C. what D. that
答案选A，none of them were carried out in their work 是非限制性定语从句，注意与上例比较句中多了一个助动词were。
(3) They put forward a lot of plans at the meeting, but none of _______ were carried out in their work.
A. which B. them
C. what D. that
答案选B，由于两句之间增加了一个并列连词but，使得该句成了一个并列句。