Verb as a part of speech in modern english Problems to be discussed

The Category of Posteriority
This category is distinguished by B. Khaimovich and Rogovskaya. As they put it this category is the system of two member opposition: shall come - should come.will come - would come
their meaning is: absolute and relative posteriority.
When posteriority is expressed in relation to the moment of speech it is called absolute. If posteriority is with regard to some other moment then it is relative.
If we accept this category, according to the definition of the grammatical category it is expressed by auxiliary verbs shall and will for absolute posteriority and should and would for relative. Shall and will cannot denote at the same time, two meanings: those of tense and posteriority, if in this case - there are two meanings then we must admit that the auxiliaries will- would, shall-should consist of two morphemes each. Applying the usual procedure we cut the words into w-ill and w-ould; sh-all and sh-ould; w-w and sh-sh are combined into morphemes of tense, and ill-all as allmorphs of the morpheme of absolute posteriority while ould-ould - as morpheme of relative posteriority.
The Categories of Number and Person
The category of person is the system of two member opposition. It is avail­able only in the Present Tense in singular number. B. Khaimovich and Rogovskaya (22) state that “the third person with a positive morpheme being opposed to the first person with a zero morpheme”. In the future tense sh- of the first person is opposed to w- of the second and third persons.
A similar treatment of the problem is observed in works of L.S. Barkhudarov (2), (4), who opposes third person to the common person (1^st, 2^nd per­sons) because “almost all the verbs in the 1^st and 2^nd persons have a zero marker”.
So far as to the category of number is concerned many grammarians consider that it is in its purity represented only in the verb “to be”, for other verbs the opposition of the 3^rd person singular, to 3^rd person plural accepted (in the present-tense).