先说宾语从句吧.由陈述句转化来的宾从由that引导,这个你清楚吧,这些时候that没有意义,只是引导作用.e.g.,Tom said (that) he was not at home.口语和非正式情况下基本就省了.定从.that在定从中可以指人和物,在定从中...