文法・語法チェック---1

文法・語法と語彙について、それぞれシリーズ化します。

今回はそのその第一段ということで。

Who did he know who sent letters by the postman?
(Goblet,p.32)
whoの役割を説明して、文章の意味を考えてみましょう。

Other people might not understand why Uncle Vernon was making a fuss about too many stamps, but Harry had lived with the Dursleys too long not to know how touchy they were about anything even slightly out of the ordinary.
(Goblet,p.33)
いわゆるtoo ... to (do)構文ですが、不定詞が否定になっています。意味を捉えることができますか。

Harry dropped his gaze to the chair in the centre of the room, the arms of which were covered in chains.(Phoenix, p137)
関係代名詞which先行詞は？またこの関係代名詞は主格、所有格それとも目的格？