Theoretical grammar of english

9. The general characteristics of the verb as a part of speech. The categories of person and number
Usually a verb is defined as a part of speech that denotes an action,
۷In modern English the verb is the only part of speech which has a developed system of categories:
- tense voice
- mood
- aspect
- number
- person
- phase
۷ It's the only part of speech that has analytical forms, plus it has some specific forms (verbals or non-fmites) which don't share all the features of this part of speech as a whole - the infinitive, the gerund, the participle.
۷ The verb combines with nouns, adverbs, prepositions in prepositional noun phrases.

The categories of person and number are closely connected with each other. In the English language the categories of person and number are expressed very poorly (слабо выражены)

In Modern English there are only a few forms indicating person and number in the synthetic forms of the verb:
1.In the present tense the expression of the category of person is divided into three peculiar subsystems:
- the first subsystem includes modal verbs that have no personal inflexions: can, may, must, shall, will, ought, need, dare. So, in the formal sense, the category of person is left unexpressed.
- The second subsystem is made up by the verb be. It has suppletive forms for different persons (singular and plural)
I- am, was
He - is, was
They, you, we - are, were
- The third subsystem presents the regular expression of person. The personal mark is confined here to the third person singular -(e)s [-z, -s, -iz], the other two persons (the first and the second) remain unmarked, e.g. comes — come, blows — blow, chooses — choose
2. The Future Simple -1 shall They will (и то уже нету такого)
The grammatical expression of number is hardly featured at all. We usually derive it from a personal pronoun.