Question

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

Answer 1

这是一个third conditional的句子阿

叫做 pass future perfect：过去将来完成时

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if he had known how it worked,

这后半句用了被动啊 he would have been told

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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）