terday.Р 2)We are going to visit the farm which his father bought in the World War Two.Р3. why代替先行词在定语从句中相当于相应的介词在从句中充当原因状语.例如:Р Who can tell me the reason why(=for which) tom was absent today?Р二、定语从句的学习难点:Р 同学们务必认真分析历届高考中有关定语从句的语言考点分布及命题轨迹,结合平时自己的薄弱环节及容易产生理解误区的内容进行归纳总结,特别需要注意以下起六个方面的学习难点:Р一)选用关系代词还是关系副词?Р 关系代词和关系副词的选择是定语从句的学习重点和难点。在定语从句中关系代词与关系副词都代替先行词在从句中充当一定的成分。如果该从句缺少主语、表语、宾语或定语,须用关系代词who,whom,whose,which,that等来引导定语从句;如果从句缺少状语时,就得选用关系副词when,where,why等来引导包含定语从句的主从复合句。切记:务必根据先行词在定语从句中所从当的成分及从句的句子结构或功能来选择相应的关系代词或关系副词。试比较:Р 1)I still remember the days which we spent in london.(注:先行词days在从句中充当spent的宾语。)Р 2)I still remember the days when we studied in london..(注:先行词days 在从句中充当时间状语。)Р 3)I still remember the days in which we studied in the same class.(注:先行词days在从句中充当前置介词in的宾语。)