which 是错误的,如果使用which那么指代的是故事一词,那么从句中的it应该去除掉.所以应该使用的词是where.The class went on with the story where they had left it before the holiday.翻译为这堂课继续这个故事,从他们放假前停止的地方开始.
问题补充：
用on which不对吗?
不对.如果用on which,那么你的思路里这个which 指代前文的什么呢?the story?或者是整个句子?如果是的话on the story?on the class went on with the story?没有这样的搭配,所以on which错误.