The subjunctive in English is used to express wishes, proposals, suggestions, or imagined situations.
The subjunctive verb usually appears in one clause in a sentence while an indicative verb appears in another clause.
In the following sentences, the verb to be is subjunctive:
They asked that you be on time tomorrow.
She wishes the teacher were more helpful.
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The subjunctive is often used in a clause that begins with that or if:
She wishes that the teacher were more helpful.
If I were rich I'd buy a sports car.