Who can be singular or plural it depends if the subject it is referring to is singular or plural Who was at the park? Sasha! Who were at the park? Sasha and her friends. Who are the people answering Sasha? Who was the person answering Sasha? We know people who live in London We know a person who lives in London. Hope that helps you?

You're confusing interrogative pronouns ('Wh--question words') with relative pronouns. 1. Question words ( Who? What? Where?): You are right that 'Who' always needs a singular verb when it's an interrogative pronoun in a subject question. For example, you say "Who wants some ice cream?" or "Who is going to the party?". You would never say "Who want...?" or "Who are...?", even if you are talking about a number of people and you know that the answer is plural. 2. Relative pronouns: (that, which, who, whom..) The above rule does not apply when 'who' is in the middle of the sentence, acting as a relative pronoun which connects two ideas and avoids repetition of a subject or object. I know a person who lives in the centre of London = "who" refers to 'a person' and needs a singular verb I know a lot of people who live in the centre of London = "who" refers to 'people' and needs a plural verb

Actually both forms can be used. In cases where we are not aware of the number of the noun that is substituted by the pronoun 'who', we are to agree the verb after it as for the 3d person singular : Who's there? Who knows? Who cares? etc. Yet, if you do know the number of the noun, we are to agree the verb correspondingly: Those students who ARE interested may attend the lecture People who LIVE there ... I do hope you'll find it helpful)))