这里实际上是一个定语从句转换过来的分词结构 把它还原一下:I heard a story which was told by my friend。 虽然前面有hear,但是hear这个动词管辖的范围在这句话到a story为止。后面的told by my friend是一个后置定语,用来修饰story的。在从句中,谓语是被动态的话,就转换为相应的-ed分词结构。 再多举个例子吧:一本由汤姆写的书:a book which is written by Tom 可以把它转换为:a book written by Tom(去掉which is,保留-ed分词)