当要区分关系代词中which 与that 时，有什么区别。如题

Some of the roads were floods ,__makes our journey more difficult.A that B which
His English ,__used to be very poor,is now excellent.A that B which

当要区分关系代词中which 与that 时，有什么区别。如题 定语从句中关系代词that 和which 要怎么分？ 关系代词that who whom whose which 和关系副词where when why的用法如何区分？ 非限定定语从句中,which可以做人的关系代词吗?吗 怎样区分关系代词和关系副词?? 怎样区分关系副词和关系代词 定语从句当先行词为人时，关系代词是which还是who，还是两个都可? 在定语从句中，如何区分宾语状语（既关系代词，关系副词） 如何区分从句中的关系代词 “介词+关系代词”构成的定语从句中，如何区分动词词组是否为固定词组？