the most far-reaching 是句子主语has been 系动词 the inexorable decline in the scope and seriousness of their arts coverage是表语Of all the changes that have taken place in English-language newspapers during the past quarter-century状语，是主---系---表句型；而that have taken place in English-language newspapers during the past quarter-century是定语从句做the changes 的定语，明白了吗？