The Subjunctive Mood

The Subjunctive mood is used in dependent clauses using the passive voice following main clauses expressing necessity, demand, request, urging, or resolution. It always involves the use of "be" where some other form of the verb "to be" would be used in the passive voice construction.

I demand the the question be answered (by him) in the sequence I taught.

Or in the active:

I demand that he answer the question in the sequence I taught. (not: that he answers the question)

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.

Demand:

I insist that I be allowed to present a minority report at the next board meeting.

You wouln't say:

In insist that I am allowed to present a minoirty report at the next board meeting.

Request:

They have asked that you be notified at once if matters do not proceed according to plan.

You wouln't say:

They have asked that you are notified at once if matters do not proceed according to plan.

The same is true for urging or resolution:

We urged that he be given a second chance to prove himsself.

The committee has resolved that the decision be deferred until the next meeting.

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So those are all uses that most native speakers have a natural feel for, but now it gets a little trickier.

When the main clause expresses a wish, you use the past tense of the verb to express the subjunctive mood:

I wish I knew how to proceed. Not: I wish I know how to proceed.

That's natural enough, but when you have a wish sentence in which the verb is a compound constructed with a form of to be, you always use 'were' to communicate a present-tense wish.

I wish I were going. Not: I wish I was going.

If you want to express a past-tense wish, use the past perfect form:

I wish she had invited me. Not: I wish she invited me

I wish they had hired you. Not: I wish they hired you.

If you want to express a future-tense wish, use would instead of will.

I wish he would arrive on time. Not: I wish he will arrive on time.

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Then you have the if clauses that state highly improbable, doubtful, or contrary-to-fact conditions:

If I knew the answer (not know), I would not have asked you.

Contrast with:

When I know the answer, I will tell you.

 

Probable: If I leave this job (as I'm likely to do), I will go to Boston.

But:

Improbable: If I were [not was]to leave this job (which is unlikely), I would want you to come with me.

The point here is that the subjunctive form should only be used when its impossible or improbable.

Probable: If she was in yesterday (and she may have been), I did not see her.

Improbable: If she had been in yesterday (she wasn't), I would have seen her.