“who”后面所跟的动词应该是单数还是复数形势.

得看情况从上下文来看,如：
Who is it?
Who are they?这两个都要看主语.与主语一致
Those who want to take.这是一个定语从句,先行词(被限定修饰名词)为those,它代表those people.为复数,遵循定语从句中的谓语须与先行词一致,所以,用want而不用wants
同理,anyone who wants to take...
anyone 先行词为单数,所以定语从句的的谓语动词与其一致须用单数wants