The subjunctive
The subjunctive is used only in select phrases or situations in English. One finds vestiges of it in certain hypothetical expressions (using "if + to be") and in certain set phrases. (In many cases the subjunctive -- considered archaic or literary -- is replaced by the modal "would," used to express the conditional.) Other meanings often communicated by the subjunctive in other languages will be expressed by modal verbs in English.
In constructions using "if + to be" the subjunctive will amount to using the form "were" (instead of "was") with the first and third persons singular ("I" and "he," "she," or "it"). (In spoken English, and in much informal writing, "was" will still be used.)
Set phrases and proverbs: