这里是rule后接宾语从句使用虚拟语气的用法。
一. 表建议，命令，请求和要求
由advise，suggest，recommend, ask, demand, desire, decide, insist , order, propose, request 等引导的宾语从句，从句谓语由 “should+动词原形” 构成。
eg. He suggested that we should leave early.
He insisted that I should go with them.
He ordered that we should go back.
二.表希望，安排，敦促，打算，想象
由 believe, expect, suspect, think, imagine，urge 等词引导的宾语从句，从句谓语由“should+动词 原形”构成,should 可省略。
eg. He urged that they go to Europe.
She desires that he do it.
Can you believe that he should kill a tiger?
三.wish 后的宾语从句
wish后接宾语从句时，要用虚拟语气。若要表示与现在事实相反的愿望，从句谓语用一般过去时或过去进行时；若表示与过去事实相反的愿望，从句谓语用would / could+have +过去分词或者过去完成时had done；若表示将来的愿望，用would (could)+动词原形。
eg. I wish she were not married.
I wished I had been rich.
I wish the train would come.
四.would rather, had rather, would soonery引导的从句
英语中这类词引导的从句通常表达一种与客观事实相违的情况，所以使用虚拟语气。表示过去时，用 “had＋过去分词”，表示现在和将来时用 “一般过去时”。
eg. I’d rather you had seen the film yesterday.
I‘d rather you went cinema tomorrow.
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