The synthetic forms of the Subjunctive Mood can be traced to the Old English period, when the Subjunctive Mood was chiefly expressed by synthetic forms. In Old English the Subjunctive Mood had a special set of inflections, different from those of the Indicative. 
In course of time most of the inflections were lost and the difference between the forms of the Subjunctive and those of the Indicative has almost disappeared. However, in Modern English there are a few synthetic forms of the Subjunctive which have survived; they are as follows: the Present Subjunctive of all the verbs.and the Past Subjunctive only of the verb to be. 
to have, to know, to speak, etc.
he, she, it be
I have, know, speak
he, she, it have, know, speak
we have, know, speak
you have, know, speak
they have, know, speak
The Past Subjunctive
to have, to know, to speak, etc.
he, he she, it were
we we were
yo you were
th they were
1)The Present Subjunctive.
In the Present Subjunctive the verb to be has the form be for all the persons singular and plural, which, differs from the corresponding forms of the Indicative Mood (the Present Indefinite). In all other verbs the forms of the Present Subjunctive differ from the corresponding forms of the Indicative Mood only in the third person singular, which in the Present Subjunctive has no ending -s.
The Present Subjunctive denotes an action referring to the present or future. This form is but seldom used in Modern English. It may be found in poetry and in elevated prose, where these forms are archaisms used with a certain stylistic aim. It is also used in scientific language and in the language of official documents, where it is a living form. 
─ Wretched is the infant’s lot,
─ Born within the straw- roof’d cot;
─ He must only be a slave.
The Present Subjunctive also occurs in some set expressions.
─ Suffice it to say that he soon came back.
─ God forbid!
In American English the Present Subjunctive is used not only in the above mentioned cases but also in colloquial language.
─ Yates called the hospital and insisted that one of the doctors come to the phone. 
2) The Past Subjunctive
In the Past Subjunctive the verb to be has the form werefor all the persons singular and plural, which in the singular differs from the corresponding form of the Indicative Mood (the Past Indefinite).
— Occasionally the form was, which coincides with the form of the Indicative Mood, can be found in the singular.
─ I know 1 am affectionate. 1 wouldn’t say it, if I wasn’t certain that I am.
The Past Subjunctive is widely used in Modern English and occurs not only in literature but also in colloquial language. 
The term ‘Past Subjunctive’ is merely traditional as in Modern English it does not necessarily express a past action. In adverbial clauses of condition it denotes an unreal condition referring to the present or future. In other types of subordinate clauses it denotes an action simultaneous with the action expressed in the principal clause; thus it may refer to the present and to the past. 
─ If I were ill I should like to be nursed by you.
─ I want to go everywhere, I wish I were a gipsy.
─ I wished he were less remote.
The analytical forms of the Subjunctive Mood
The analytical forms of the Subjunctive Mood consist of the mood auxiliaries should, would, may (might) or shall (which is seldom used) and the infinitive of the notional verb.
─ Mr. Barkis... proposed that my pocket-handkerchief should be spread upon the horse’s back to dry.
─ Yates wished' Bing would stop thanking him, but Bing went on.
─ Whoever you may be, Sir, 1 am deeply grateful to you.
─ She lowered the blind and closed the shutters that he might not see the sun set.
─ I propose that you shall comealong with me. 
Mood auxiliaries have developed from modal verbs, which have lost their modality and serve to form the analytical Subjunctive. Still there are cases when mood auxiliaries retain a shade of modality, for instance the verb mightin adverbial clauses of purpose.
─ Lizzie stood upon the causeway that her father might seeher.
In modern English the same meaning as is expressed by the Subjunctive Mood may also be rendered by the forms of the Indicative Mood — the Past Indefinite, the Past Perfect and occasionally the Past Continuous and the Past Perfect Continuous. 
In adverbial clauses of condition the Past Indefinite denotes an unreal condition referring to the present or future; the Past Perfect denotes an unreal condition referring to the past.
─ The room is so low that the head of the tallest of the visitors would touch the blackened ceiling if he stood upright.
─ The noise about her was frightful, so deafening that if she had shouted aloud she would not have heard her own voice.
In other types of subordinate clauses the Past Indefinite' denotes an action simultaneous with the action expressed in the principal clause; the Past Perfect denotes an action prior to that of the principal clause. 
─ He (Mr. Barkis) sat looking at the horse’s ears as if he saw something new there.
─ I felt as if the visit had diminished the separation between Ado and me.
The Past Continuous and the Past Perfect Continuous are less frequently used.
─ They looked as if they were fighting for their life.
─ The mother’s delicate eyelids were pink, as if she had been crying half the night.
—In some grammars these forms are considered 'to be the forms of the Subjunctive Mood, homonymous with the forms of the Indicative Mood. 
- H. Sweet «A new English grammar» Oxford, 1988
- Kaushanskaya “A Grammar of the English Language” 1967
- Murphy R. «Grammar in Use» Press Oxford Univ. 2000
- Shaw. B. “The Millionaires”. 1965. Moscow.
- Trollope. A. “Cousin Henry”. 1979. Moscow.
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- Wells. H. G. “The Island of Doctor Moreau”. 1986. Moscow.