Stave said that if he had known how it worked,he would have

这是一个third conditional的句子阿叫做 pass future perfect：过去将来完成时-----------------if he had known how it worked,这后半句用了被动啊 he would have been told-----------------抛开句意原来应该是 if he/she had done,he/she would have done一般用来描述---如果某人在过去已经完成了某事的话,某人就不会（失败,破产。。。等等）