The present subjunctive is like the bare form of the infinitive, so with most verbs you'll only notice it in the third person singular where it doesn't take -s, but the verb to be is noticeable because we use be for all persons. In the past subjunctive, you can only see it clearly with to be again; it uses were for all persons.
In British English, the present subjunctive is not that common; it is used sometimes in formal speech and you will hear it used by journalists and politicians on the news when they want to sound solemn or dignified. It does survivein a number of expressions like 'Long live the king' and 'God help you'. Even the past subjunctive in 'If I were you' is not used by many speakers, though it is preferred in formal contexts and by grammarians. I'd still recommend using it; you won't offend anyone and will please some. Also some exams accept 'If I was you', but not all- I think Gmat regard it as wrong.
In BrE, the present subjunctive is certainly in decline- apart from fossilised expressions, most people never use it, but it is used more in AmE. Some, like this article, argue that the subjunctive is defunct, but this kind of position will always bring the subjunctive's supporters out.
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