The problem of parts of speech is one that causes great controversies both in general linguistic theory and in the analysis of separate languages. We shall have to examine here briefly a few general questions concerning parts of speech which are of some importance for Modern English.

Besides the synthetical and analytical means of building word forms in Modern English, there is yet another way of building them which stands quite apart and is found in a very limited number of cases only.

By sound alternations we mean a way of expressing grammatical categories which consists in changing a sound inside the root. This method appears in Modern English, for example, in nouns, as when the root vowel [ae] of the singular form man is changed into [e] to form the plural men, or similarly the root vowel [au] of mouse is changed into [aı] in mice, and a few more cases of the same kind.

These fall under two main headings, (a) those limited to changes in the body of the word, without having recourse to auxiliary words (synthetic types), (b) those implying the use of auxiliary words (analytical types). Besides, there are a few special cases of different forms of a word being derived from altogether different stems.

It should be noted that there is some confusion in the use of the terms "suffix" and "inflection" or "ending".

The morpheme is one of the central notions of grammatical theory, without which no serious attempt at grammatical study can be made. Definition of a morpheme is not an easy matter, and it has been attempted many times by different scholars.

Perfect Tense

Simple Tense

Как процесс определенной продолжительности.

Как факт к определенному моменту времени.