The buses, were already full, were surrounded by anxious people.
A. all of them
B. all of which
C. they all
D. all which
网友回答
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。