Third person singular. The third person singular regular verbs in the present tense in English are distinguished by the suffix -s. Run → runs.

If the base ends in one of the sibilant sounds, and its spelling does not end in a silent E, the suffix is written -es: catch → catches. If the base ends in a consonant plus y, the y changes to an i and -es is affixed to the end: cry → cries. English preserves a number of preterite-present verbs, such as can and may. These verbs lack a separate form for the third person singular: she can, she may.

Preterite form (second form)

The preterite form is used in all persons and numbers as the finite verb in a clause, typically to talk about the past. It can also be used in a dependent clause to indicate that a present-time situation is hypothetical. In spelling, the regular preterite is formed by adding ed to the bare form (play → played). Irregular verbs have separate preterites and form the list of English irregular verbs.

Past participle. In regular weak verbs, the past participle is always the same as the preterite.

• The past participle is used with the auxiliary have for the English perfect constructions: They have written about the slap of tails on water, about the scent of the lodge... 

• With be or get, it forms the passive voice : Trees sometimes get gnawed down by beavers.

• It is used as an adjective. For transitive verbs, it is used as a passive: the written word (=the word that has been written). For intransitive verbs, it is used as a perfect: a fallen tree (=a tree that has fallen).

Present participle The present participle is formed by adding the suffix -ing to the base form: go → going.

• The present participle is used to form a past, present or future tense with progressive or imperfective aspect: He is writing another long book about beavers.

• adverb: He is writing quickly.

• adjective: It is a thrilling book.

  • personal pronoun: Her thrilling novel.

Gerund .The English gerund is that form of a verb that acts as a noun but retains its identity as a verb.

The gerund can often be distinguished from the present participle by inserting the words the act of before it: I enjoy [the act of] drinking wine.

Modal constructions

The English modal verbs are would, will, should, shall, may, might, can, could, must, ought, had better, dare, and need, and are used to express probability, insistence or refusal, habitual action, suggestion, conditional action, etc.

For example, will and would can be used with a different meaning to futurity or conditionality: I will not do it! (refusal, i.e. negative insistence); I would not do that (if I were you). (suggestion, or implied conditional action)

Functions. In addition to conveying the content of an action or state, verbs in English can convey tense, aspect, mood and other modality, and voice.

Tense refers to the grammatical expression of the time (past, present, or future) of an action or state.

Modality refers to the attitude of the speaker toward the action or state, and mood is the inflectional expression of modality. These attitudes generally involve degrees of desirability and possibility.

The indicative mood is the usual mood, which indicates a declaration without indicating that it is desired, counterfactual, or a command.

The imperative mood is used for commands, as in the second person construction Go there now in which the implied subject you is omitted and in which the bare form of the verb is used. English sometimes marks the subjunctive mood of desire in dependent clauses by using the base form of the verb rather than an inflected form,

Voice expresses the relation between the verb's subject and the action.

English expresses two voices: active and passive. The active voice conveys that the subject is the one undertaking the action, as in I see her. The passive voice conveys that the action is being received by the subject, and uses a helping verb with the passive participle: I am seen (by her).