The subjunctive is a special kind of present tense which has no –s marking in the third person singular. The subjunctive was very common in English many centuries ago. It is still common in American English after words like suggest, recommend, ask, insist, vital, essential and important.
Study the following sentences. Note the use of have with singular subjects. The same verb forms are used in both present and past sentences.
I suggest that she accept the offer.
I insist that she reveal her sources.
It is essential that every child have the same opportunities.
The judge recommended that the accused remain in jail for at least five days.
In subjunctive mood, be is used as it is.
I insist that she be freed.
In British English, subjunctive structures are formal and unusual. In that-clauses, British people usually use should + infinitive. Subjunctive forms with should are also used in American English.
I suggest that she should accept the offer.
I insist that she should reveal her sources.
It is essential that every child should have the same opportunities.
The judge recommended that the accused should remain in jail for at least five days.
I insisted that she should be freed.