Historical development of analytical forms of the verbs in English.
In the OE language there was no form of the Future tense. The category of Tense consisted of two members: Past and Present. The Present Tense could indicate both present and future actions, depending on the context.
there was another way of presenting future actions — modal phrases consisting of verbs «sculan, willan, magan, cunnan»(NE shall, will, may, can) and the Infinitive of the notional verb.
In these phrases the meaning of the futurity was combined with strong modal meanings of volition, obligation and possibility.
In ME the use of modal phrases, especially with the verb «shall» became increasingly common. «shall» plus Infinitive was not the principal means of indicating future actions in any context. «Shall» could retain its modal meaning of necessity, but often weakened it to such an extent that the phrase denoted «pure» futurity.
In late ME texts «shall» was used both as a modal verb and as a Future Tense auxiliary. Future actions were also commonly expressed by ME «willen» with an Infinitive, but the meaning of volition in «will» must have been more obvious than the modal meaning of «shall».
In the times of Shakespeare the phrases with «shall» and «will» occured in free variation. They can express «pure» futurity and add different shades of modal meanings. Phrases with «will» and «shall» outnumbered all the other ways in indicating futurity.
In OE there were 12 modals, In ME — 2 most frequently used modals «shall» and «will».
Like other analytical forms of the verb, the Perfect forms have developed from OE verb phrases. The main source of the Perf.form was the OE «possessive» construction, consisting of the verb «habban» (NE «have»), a direct object and the Participle II of a transitive verb, which served as an attribute to the object.
The meaning of the construction was: a person (subject) possessed a thing (object), which was characterized by a certain state resulting from the previous action (the participle).
Towards ME it turned into analytical forms and made up a single set of forms termed «perfect».
In the Perfect form the auxiliary «have» had lost the meaning of possession and was used with all kinds of verbs.
In the beginning the main function of the Perfect forms was to indicate a completed action, to express «perfectivity» rather than priority of one action to another.
As for the Continuous forms it should be said the following.
Verb phrases consisting of «beon» (NE «be») plus Participle I are not infrequently found in OE prose. They denoted a quality or a lasting state.
In Early ME «beon» plus Participle I fell into disuse. It occured occasionally in some dialectal areas.
In the 15th and 16th centuries «be» plus Participle I was often confused with a synonimous phrase – «be» plus the preposition «on» plus a verbal noun.
By that time the Present Participle and the verbal noun had lost their formal differences: the Participle I was built with the help of -ing, and the verbal noun had the word-building suffix — ing.
The prepositional phrase indicated a process taking place at a certain period of time. It is believed that the meaning of process or an action of limited duration — which the Continuous forms acquired in Early NE — may have come from the prepositional phrase.