【正确答案】 A

【答案解析】[精解] 本题考查固定搭配。从文中判断，英国人会抓住一切机会不厌其烦地讨论天气。at length 意为“详尽，充分的”符合题意，如：He went on at tedious length about his favourite hobby。to a great extent 意为“很大程度上”，如：To a great extent，he is correct。from their heart 意为“发自内心的”，如：I love you from my heart。by all means 意为“尽一切办法，一定”，如：Please save her by all means。