其实就跟中文的缩句一样,你找出主谓宾的主句,其他就是从句. 举个定语从句的例子 A prosperity which / that had never been seen before appears in the countryside. 这个的主句就是A prosperity appears in the countryside.那多下来的就是从句,因为修饰的是主语,就是定语从句.不过这个是比较简单的例子,往往英语越高级的考试,一句长句里会套很多从句,就要好好判断了,而且有时会按照美式的说法,省掉很多提示性介词,比如which,that,那就很难,需要一定的功底,才能判断.
