In that clauses following verbs expressing “suggestion, demand, command, or necessity,” use the present subjunctive (the base form) or should + the base form.
Basic Rules
Present subjunctive: The verb in the that clause is in the base form (regardless of person, number, or tense).
“It's necessary that every student be present.”（It is necessary for every student to be present.）
“The doctor suggested that she rest for a week.”（The doctor recommended that she rest for one week.）
Verbs and adjectives that take this construction:
- Verbs: suggest / propose / recommend / insist / demand / require / request / order / urge
- Adjectives: necessary / important / essential / vital / advisable / natural / strange
He suggested that the meeting be postponed.（He proposed postponing the meeting.）
It is essential that all members attend the ceremony.（It is essential for everyone to attend.）
The committee demanded that the report be submitted by Friday.（The committee demanded that it be submitted by Friday.）
Points to Note
① Use the base form even with the third-person singular: The present subjunctive does not take -s. “It is important that he attend（× attends）the meeting.”
② Note the use of insist: To state a fact = that + indicative mood; to make a demand = that + subjunctive. “He insisted that he was innocent.”（He claimed that he was innocent.）vs “He insisted that the meeting be cancelled.”（He demanded that the meeting be cancelled.）
③ Omission of should: In American English, should is often omitted and only the base form is used. should + the base form is also correct.
④ Use the base form in the passive voice as well: “It is necessary that the documents be signed.”（The documents need to be signed.）
- Suggestion or demand verb（suggest/demand/insist, etc.）+ that + S + base form
- It is necessary/important/essential + that + S + base form
- Do not add -s even with the third-person singular
- should + the base form has the same meaning（British English style）
- The meaning of insist depends on whether the context expresses a fact or a demand
Practice
- Translate “The doctor recommended that he start exercising” into English using suggest（present subjunctive）.
- Translate “It is essential that all application forms be submitted by next week” using It is essential that ... .
- Decide whether insist expresses a statement of fact or a demand, and translate it into English: She insisted that the window be left open.