以下の文例の内、接続詞を伴う等位関係とは文例[5a]、接続詞を伴わない等位関係とは文例[3a]、副詞的従位関係とは文例[3b] と [5b]である。

He got lost on Snowdon, which was enveloped in fog. [3]
He got lost on Snowdon; it was enveloped in fog. [3a]
He got lost on Snowdon, when it was enveloped in fog. [3b]
My brother, who has lived in America since boyhood, can still speak fluent Italian. [5]
My brother can still speak fluent Italian, and he has lived in America since boyhood. [5a]
My brother can still speak fluent Italian although he has lived in America since boyhood. [5b]                                           (CGEL、17.23) （下線は引用者）