The buses were already full were surrounded by anxious people.A. all of themB. all of w

问题补充：

The buses, were already full, were surrounded by anxious people.

A. all of them

B. all of which

C. they all

D. all which

答案：

A. all of them

(答案→)B. all of which

C. they all

D. all which

解析：句意：公共汽车，已经都满了，被焦急的人群包围。这里含有一个定语从句，分析句子结构可知，该空所填词用来引导定语从句，选B。