Практическая грамматика

§ 7. As has already been mentioned, the verb has the grammatical categories of person, number, tense, aspect, voice, and mood.
In Modern English there are but few forms indicating person and number in the synthetic forms of the verb. These are:
1.The third person singular Present Indefinite Indicative– he speaks.
2. The Future Indefinite tense:
I shall speak We shall speak
He will speak They will speak
The verb to be has suppletive forms for different persons (singular and plural).
I am, was We 
He is, was You  are, were
They 
§ 8. The category of tense is very clearly expressed in the forms of the English verb. This category denotes the relation of the action either to the moment of speaking or to some definite moment in the past or future. The category of tense and the category of aspect are intermingled.
The category of aspect shows the way in which the action develops, whether it is in progress or completed, etc. In Russian the category of aspect predominates, and the category of tense is subordinated to it. In English contrariwise the category of tense predominates and aspect is subordinated to it. Some of the English tenses denote time relations, others denote both time and aspect relations. There are four groups of tenses: Indefinite, Continuous, Perfect and Perfect Continuous. The Indefinite form has no aspect characteristics whatever, the Continuous, Perfect and Perfect Continuous forms denote both time and aspect relations. Each of these forms includes four tenses: Present, Past, Future and Future in the Past, i.e. future from the point of view of the past. Thus there are 16 tenses in English.
§ 9. Voice is the category of the verb, which indicates the relation of the predicate to the subject and the object.
There are three voices in English: the active voice, the passive voice and the neuter-reflexive voice.
The active voice shows that the person or thing denoted by the subject is the doer of the action expressed by the predicate.
The passive voice shows that the person or thing denoted by the subject is acted upon.
The neuter-reflexive voice shows that the action expressed by the predicate passes on to the subject. This voice is formed by means of a reflexive pronoun.
Helen lifted herself up and looked towards nurse. (Gaskell)
The truth was, Mary was dressing herself. (Gaskell)