2.虚拟语气用在主语从句中
a. It is/was +adj.+ that+主语+should do (should可以省略)
adj:advisable,amazing,astonishing,better,clear,certain,desirable,good,interesting,impo-ssible,normal,necessary,possible…
It is natural that he (should) think so.
It was necessary that the plan should be planned carefully.
b. It is/ was+ n.+ that+主语+should do(should可以省略)
①表示“惊奇、怀疑、遗憾”等意义的名词词组，如: a fact, a good thing, a pity, a shame, a wonder …
②表示“请求、命令、建议、决心”等意义的名词，如advice, demand, decision, order, proposal, requirement, suggestion …
It is a pity she should say so.
It was her order that the matter should be discussed.
③ It is/was+过去分词+that+主语+should do(should可以省略)
用在该句型中的动词过去分词表示“请求、命令、建议”等。
It is requested that Miss Li should give a performance at the party.
④It is (high) time that+主语+did/should do，should不可以省略
到做……的时间了。
