The subjunctive is usually the third-person form of the verb with the ‑s dropped. When using the verb to be in the subjunctive, the present tense is be, and the past tense is were.
The subjunctive is used after certain expressions which imply a good or bad quality, or an imperative, and which create a strong mood. The subjunctive verb often comes after an expression which can be followed by the word that (e.g. it is best that, and it is essential that).
It is recommended that he uses the subjunctive properly.
It is recommended that he use the subjunctive properly.
It is vital that I be at my best at all times.
The present tense be is used here because it’s an indefinite time period (see Simple Present).
The subjunctive is usually used with verbs like desire, ask, and require, where whatever is desired or asked or required may not actually be done.
Maya insisted that the student seek the aid of a tutor.
It was proposed by the gunman that the victim remain lying on the ground.
Conditional sentences can also use the subjunctive.
If there were a quiz tomorrow, I would study tonight.