The subjunctive was formerly used in English for situations that were improbable or that expressed a wish. It is only rarely used in modern British English. It is, however, found in certain set phrases and in very formal forms of speech and writing. God save the Queen! Heaven help us! Heaven forbid that that should happen to me.
The subjunctive is an indispensable means of expression in French. Its use is much more prevalent in French than in English, where an infinitive is often used instead. The subjunctive is a mood used to express an action that is dependent on a subjective idea, opinion, or condition.