(一)下列动词的费宾语从句中用should do
order.ask.decide.demand,require,recommand,suggest,insist,advise
eg:He suggested that we should have a fancy dress party.
(二)suggestion,order,request,demand.importance,proposal等引导的同位语从句用should do 引导的虚拟。
eg:I think it is a thing of importance that it should be done soon.
这个应该和你的问题是吻合的吧。
追问应该就是表示要求,命令类的词语吧?