who 引导的定语从句后接的动词用的是第三人称单数么?

那不一定呀,应该看前面的先行词是单数还是复数,前面的先行词如果是单数,后面的谓语动词就要用单数,前面的先行词如果是复数,后面的谓语动词就要用复数,记住应该与前面的先行词保持一致.如
He who doesn't get to the Great Wall isn't a true man.
Those who come first will get more.先来多得