内容介绍：主语从句名词 性宾语从句从句 表语从句同位语从句常用关联词: that, if, whether, who,whom, whose, what, which, when,where, how, how many, how far, why等. 常用关联词: 连词：that, if, whether, as if, asthough.that 无词义，在从句中不担任成分，有时可省略；if(whe