look at this group of people playing beach volleyball中playing beach volleyball 是什么成分?如果加上be动词,应该加is 还是are

问题描述:

look at this group of people playing beach volleyball中playing beach volleyball 是什么成分?
如果加上be动词,应该加is 还是are

is
动名词作主语谓语动词用单数
playing beach volleyball是形式主语