先行词是表示时间的词如time，year， day等且在定语从句中做时间状语，用关系副词whenI will never forget the day when I joined the Party.先行词是表示地点的词如place，factory，hospital等且在定语从句中做地点状语，用关系副词whereThis is the factory where my father works.先行词是reason，且在定语从句中做原因状语，用关系副词whyThat's the reason why he looks so old....
