what到底能不能引导定语从句She told them what she had seen there They are building a second library in what was once the school cinemaWhat was impossible 50 years ago may be quite possible today这个句子中,what引导了什么从句最后一个我认为是主语从句最好把从句的判定都解释下
问题描述：
what到底能不能引导定语从句
She told them what she had seen there
They are building a second library in what was once the school cinema
What was impossible 50 years ago may be quite possible today
这个句子中,what引导了什么从句
最后一个我认为是主语从句
最好把从句的判定都解释下
答
what不能引导定语从句
第一个是宾语从句
第二个是定语从句，是由in what引导的
第三个是主语从句
答
what 是缩合关系代词，即先行词和关系代词的结合体。头两句从意义上来说是定语从句，但从结构上来说相当于名词从句。可以理解为the things that ,all that ,something that ，它已经把先行词和关系代词结合了，你自己套进题里看看。注意用what 引导定语从句时前面不能有名词。
答
what不能引导定语从句.第一个是宾语从句,what she had seen there作told的宾语.第二句是定语从句,但是有问题,没有in what的,应该是in which,which指代先行词library,in the second library was once the school cine...
答
1宾语，2定语，3主语