主语从句导入:观察并指出句子成分A tree has fallen across the road. You are a student. To find your way can be a problem. Smoking is bad for you.一 概念:主语:主语是指句子谈论的主题,说明的人或事物。也就是句中动作、行为、性质和状态的主体,一般位于句首主语从句:在句中充当主语的从句二基本结构 关系词 简单句 谓语动词 宾语 同位语That he finished writing the composition in such a short time surprised us all.他在很短的时间内写完作文让我们都很惊讶三 关系词(引导词)1 从属连词:that whether that 引导主语从句只起引导作用,本身无实际意义,在主语从句中不充当任何成分,但不能省略