— Who are those people gathering in front of the building?
— A group itself the youth volunteers.
A. calling
B. calls
C. called
D. to be called
网友回答
A. calling
B. calls
C. called
D. to be called
解析：考查分词做定语。本题的动词call与a group构成主动关系，故使用现在分词的形式。句意：—聚集在大楼前面的那些人是谁啊？—一一群自称为青年自愿者的人。故A正确。