英语定语从句中that,which,who,那些时候只能用that而不能用后两个?答:1)先行词是不定代词:all,few,little, much,something,nothing,anything等。All that we have to do is to practise every day.2)先行词被序数词或形容词最高级所修饰。The first lesson that I learned will never be forgotten.3)先行词被all,any,every, each, few,little,no,some, 等修饰...