who做主语的，后面接动词三单形式；
who不是做主语的，后面动词的形式要看主语来决定；
who
pron.谁;(询问姓名、身份或职务)什么人;表示所指的人;进一步提供有关某人的信息
Health care must be at the service of all who need it.
医疗保健机构必须为所有需要者提供服务。
Who was it that won the US Open?
在美国公开赛上获胜的是谁？
She made it her business to find out who was responsible.
她一定要查清楚到底该谁负责。
Who could forget his speech at last year's party?
谁能忘记他去年在聚会上的讲话呢？
Who sets the standard for water quality?
水质标准由谁来制订？
温馨提示：
