请问虚拟语气中的should在什么情况下可以省略,

请问虚拟语气中的should在什么情况下可以省略,

1.在表示建议,要求,命令,想法的动词后的从句里,用should + 动词原形,should 可以省略.如 advise,agree,command,decide,demand,determine,grant,indicate,insist,order,prefer,propose,request,require,stipulate,suggest,urge,vote.常考到的是:suggest,advise,demand,require,propose,insist,order,request.
His doctor suggested that he (should) take short leave of absence.
The author proposed that TV (should) be turned off at least one hour every day.
2.在表示建议,要求,命令,想法的名词后的从句里,用should + 动词原形,should可以省略.如 advice,decision,agreement,command,decree,demand,determination,indication,insistence,order,preference,proposal,request,requirement,stipulation etc.
It was Bill’s suggestion that everyone (should) have a map.
His suggestion was that everyone (should) have a map.
He gave us a suggestion that everyone (should) have a map.
3.在It is/was +形容词后的that 从句中用should的结构,should 可以省略.这类形容词常见的有:advisable,anxious,compulsory,crucial,desirable,eager,essential,fitting,imperative(绝对必要),impossible,improper,important,natural,necessary,obligatory,possible,preferable,probable,recommended,urgent,vital etc.
It‘s natural that she (should) do so.
It is essential that we (should) tell her the news.
4.在 lest 和 for fear that(以免),in case(以防)从句中用should,should 可以省略.
She walked quietly lest she (should) wake up her roommates.
Have your gun ready in case we should need it.