4. The buses, most of _________ were already full, were surrounded by an angry crowd.

A. that B. it C. them D. which

【陷阱】容易误选 C，用 them 代指 the buses。

【分析】最佳答案是D。most of which were already full 为非限制性定语从句，修饰 the buses。类似地，以下各题也选D：

(1) His house, for _________ he paid $10, 000, is now worth $50, 000.

A. that B. it C. them D. which

(2) Ashdown forest, through _________ we’ll be driving, isn’t a forest any longer.

A. that B. it C. them D. which

(3) This I did at nine o’clock, after _________ I sat reading the paper.

A. that B. it C. them D. which

类似地，以下各题选 whom，不选 them：

(4) George, with _________ I played tennis on Sundays, was a warm-hearted person.

A. that B. him C. them D. whom

(5) Her sons, both of _________ work abroad, will come back home this summer.

A. that B. who C. them D. whom

(6) I met the fruit-pickers, several of _________ were still university students.

A. that B. who C. them D. whom

5. He had a lot of friends, only a few of _________ invited to his wedding.

A. whom B. them C. which D. who

【陷阱】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。

6. On Sundays there were a lot of children playing in the park, _________ parents seated together joking.

A. their B. whose C. which D. that

【陷阱】容易误选B，认为这是非限制性定语从句。