one表示泛指,that和it 表示特指that与所指名词为同类,但不是同一个it 与所指名词为同一个。 I cant find my hat. I think I must buy one.(不定) 我找不到我的帽子了。我想我该去买一顶。 The hat you bought is bigger than that I bought.(同类但不同个) 你买的那顶帽子比我买的大。 I cant find my hat. I don t know where I put it.( 同一物) 我找不到我的帽子。我不知道我把它放在哪了。 Meeting my uncle after all these years was an unforgettable moment,_ I will always treasure(NMET2002) Athat Bone Cit Dwhat 此题的正确答案为B,这里one作代词,指代a moment,在句中作an unforgettable