who is talking？ who are talking？哪个对

Tom,Mary and Peter are talking happily. 主语划线提问，难道不是who are talking?吗

who is talking 对 who可以看成是第三人称单数
你提问之前肯定不知道你问的“谁”是单数还是复数，难道一句话用单数还是复数还要根据回答来确定吗，这是不可能的。
who就是第三人称单数，所以用is

Who are talking happily?

who is talking ? 对的

who is talking? 谁在说？ 双语例句 1 the man who is talking with a group of students is our class teacher. 正在和一群学生谈话的那个人是我们的班主任。 2 the rather strong man who is talking with our headmaster is a footballplayer. 在和我们校长讲话的那个相当健壮的人是个足球运动员。 please give this letter to that man, who is talking to your father. 请把这封信交给那个人，他在和你的爸爸说话。 4 it's so late. who is talking there? oh, nobody there. 这么晚了，是谁在讲话呢？没有人啊。