应该是are 吧。 不过我没有百分之百的把握喔
He is one of
my favorite singers who are singing on the stage
他是
我最喜欢的台上歌手们
的其中一个
who are singing on the stage 不是形容 "he" 的
是形容 my favorite singers
所以负数用are
are 修饰的先行词是 my favorite singers
还有一个句子 He is the only one who____
late for school.就填 is
are
先行词是singers,复数