I counted the people the activity, and there were 286 of them.
A. were taking part in
B. taking part in
C. taken part in
D. took part in
网友回答
A. were taking part in
(答案→)B. taking part in
C. taken part in
D. took part in
解析：因为这个句子已经有谓语动词，句子中又没有连词故空格处应用它的非谓语动词，people与 take part in之间是主动关系，故选B.