定语从句that是不是哪都可以用

关系代词只能用that情况：先行词是不定代词 all,few,little,much,something,nothing,anything,etc。先行词被序数词和形容词最高级修饰先行词被the only,the very,the same,the last等修饰先行词被all,any every,each,few,little,no,some等修饰先行词中既有人又有物句子中已有who等,避免重复关系代词在从句中作表语这些要像记公式一样记住~