He is the only one of the students who has been invited to the English Evening.这句话有错吗?错在哪先行词被the only,the very,the same等修饰时,后面只能用that.

你好。应该是
He is the only one of the students THAT has been invited to the English Evening.

---------但是，在现今的英语中，就你的句子来说， that / who的界限没有那么讲究了。连英语民族都很少考虑它们的界限了。

应该用have

这个句子没错。当先行词被 the only ,the very 修饰时。如果被修饰词不是人而是物必需用that,而不用which.但当先行词为人时。多数用who.

没有错啊。至于你后面说的那个，我倒是没听说过。

先行词被the only,the very,the last,the just,the same 等修饰时,不管先行词指人还是指事物,引导词都用that.例如：
You’ve the only person that I met here.你是我在这儿遇见的唯一的一个人.
This is the very shirt that I am looking for.这正是我一直在寻找的衬衫.
所以,你的这个句子应该是：
He is the only one of the students that has been invited to the English Evening.