In form the indicative and the subjunctive differ in the present and the past tenses of the verb to be, as follows:

Indicative of be
Present Past
I amWe areI wasWe were
You are You areYou were You were
He isThey are He wasThey were
Subjunctive of be
Present Past
If I beIf we beIf I wereIf we were
If you be If you beIf you were If you were
If he beIf they be If he wereIf they were

Other verbs in the subjunctive mode do not end in s in the third person singular number, but use the same form as the other persons in the singular number; as, if he go, if she walk.

If, though, although, or lest usually introduce the subjunctive form.

In modern English, the use of the subjunctive is becoming rare except in the past and past perfect tenses in statements contrary to fact, and in wishes, which are really statements contrary to fact; as,

1. If I were a king (but I'm not), I'd see that my laws were obeyed.

2. I wish I were a king! (but I'm not).

3. If I had been careful, my work would be good. (I was not careful.)

4. I wish I had been careful! (I was not.)

Notice that the verb is in the past or in the past perfect tense.