主语开头的就是主句,主句前不能有连词,那么有了连词就是从句了。主语是句子的中心,从名是修饰主句或句中的某些成分的,充当名词、副词、形容词用,将其改这相应的名词、副词、形容词亦可,如果去掉从句主要意思仍完整,如: That he is a student is true.可以将从句That he is a student 用it代替,即It is true. The book which is red is mine.可改成The red book is mine.用 red 代替从句which is red. I am a student when I was 7years old.可改成I am a student that time.用that time代替从句when I was 7years old。 The book (which)I bought yesterday is red.这句主要说的是:这本书是红的,去掉(which)I bought yesterday 意思还完整,所以(which)I bought yesterday 是从句。
有引导词(从属连词)的句子就是从句。反之亦然。 例:I am a student when I was 7years old. 这句话中的引导词(从属连词)是when。从句的句型是引导词+句子。所以when I was 7years old是从句。 当然,事有例外,当从句为宾语从句时,引导词可为that,可省略。 (引导词是初中时候说的,从属连词是高中时候说的。具体用哪个你自己看下。我也是初二学生,希望可以帮助到你)本回答被网友采纳