one的用法Having a chat with an old friend you have not seen for

one 指代“和十年未见的老朋友交谈是一件非常愉快的事情”这个事实.
不是定语从句.定语从句要满足有先行词,而该句子并没有先行词.
a pleasant thing 绝不是先行词,你认真体会一下.
定语从句中的先行词指的是定语从句所要修饰的确切的名词.举一个非限制性定语从句中用which的情况.My house,which I bought last year,had a lovely
garden.非限制性定语从句是对先行词的补充说明,把which I bought last year删除后,句意仍完整.还有一种情况,从句时否定句时或谓语有复合宾语时
常用which.Jim was always speaking highly of his role in the play,which,of course,made the others unhappy.这种用法里,which前后都要有逗号单独隔开.
这个问题问得非常好!值得大家一起探讨
我认为答案是one,没错