Basic grammar question - Present perfect

Hi @AtomChip,

Weolcome to GMATclub.

Subjunctive mood - Necessity:

It is necessary that these questions be answered at once.

It is necessary that he answer these questions at once.

You wouln't say:

It is necessary that these question are answered at once.

It is necessary that he answers these questions at once.

6 Forms of the Subjunctive Mood

1. Counterfactual
In this subjunctive construction, the writer expresses a notion contrary to fact, such as “If I were you, I’d return it to the store.”

2. Imperative
In this class of the subjunctive mood, commands and demands are expressed: “I demanded that she walk away.”

3. Necessity
This subjunctive form refers to requirement: “It is necessary that she fill out the form first.”

4. Proposition
This category applies to proposals and suggestions: “We proposed that they reconsider the offer.”

5. Supposition
In this form, the writer expresses a possibility: “If I were to accept the position, I’d have to relocate.”

6. Wish
This type of subjunctive form deals with expressions of desire: “I wish that I were able to go back and do it over again.”

The subjunctive case also survives in such idiomatic phrases as “as it were,” “be that as it may,” “be they [one thing or another],” and “would that it were.”

Hope this helps!