which一般用在非限制性定语从句中,例如He invited us to dinner, which was very kind of him.
他邀请我们吃晚饭,他这么做真是太客气了.
在本句中,首先说这个故事是个比较悲伤的故事,然后说了原因,为什么是悲伤的呢,因为在这个故事中,男主角死于白血病.此时后面的句子你可以转换成The hero finally died of leukemia in this story. 你如果用which的话,后面的句子which the hero finally died of leukemia,你仔细分析一下这句话的语法就不对了.
希望您能够明白我想表达的意思,祝学习进步.