The subjunctive mood scarcely exists in present day English. It is marked by distinctive verb forms which are now confined to the verb be and third person singular forms of other verbs. Note that the subjunctive forms still exist in American English.

The following are the forms of the subjunctive.

Present subjunctive

The verb be has the following forms in the present subjunctive mood:

I be (NOT I am)
You be (NOT You are)
We be
They be
He be

Third person singular verbs in the present subjunctive mood have the following forms:

I speak
You speak
We speak
He speak (NOT He speaks)
She speak (NOT She speaks)
They speak

Past subjunctive

The verb be in the past subjunctive mood has the following forms:

I were (NOT I was)
You were
They were
We were
He were (NOT He was)

Third person singular verbs in the past subjunctive mood has the following forms:

I spoke
You spoke
They spoke
We spoke
He spoke

Note that only a few verbs like suggest, propose, demand or insist can be followed by a subjunctive form.

I suggest that he consult a doctor.
They demanded that she disclose the information.
I insist that I be freed.

Note that these verbs in the indicative mood are followed by forms like consults, discloses and am.

In British English, the indicative forms are almost always used. In American English, however, subjunctive forms are still used. But since they are likely to cause confusion, speakers often insert the modal should as in the following examples.

I suggest that he should consult a doctor.
They demanded that she should disclose the information.
I insist that I should be freed.

The past subjunctive is still used in the following cases.

After the verb wish

The past subjunctive verb forms are sometimes used after the verb wish to indicate that a situation is unreal or imaginary.

I wish I were a millionaire. (= I am sorry that I am not a millionaire.)

After if

If I were you I wouldn’t do it. (Indicative mood: If I was you I wouldn’t do it.)

After ‘it is time + subject’

It is time we started.

After would rather + subject
This structure indicates preference.

I would rather you went by train. (= I should prefer you to go by train.)