Contextual semantic functions of the nuclear sentence patterns in expending the communicative intention of the speaker and ways of their teaching

English verbs possess a number of properties that make them somewhat unusual among other Germanic languages. All English verbs can be derived from a maximum of three principal parts. This represents an extensive paring down of the inflectional categories of the more conservative Germanic languages. Because of this, the strict distinction between transitive verbs and intransitive verbs observed in some other languages find no part in English grammar. In English, both of these sentences are equally possible: The water is boiling. (effectively, a middle voice; compare the water is being boiled.) And The chef is boiling the water.
English formerly possessed inflections that allowed transitive and intransitive verbs to be distinguished. A few of these distinctions were incorporated into the lexicon: e.g. fall vs. fell (cause to fall); lie vs. lay (cause to lie). Modern English verbs freely switch their valence and can take from zero to two predicates if they are supportable by the meaning:
She gives. She gives books. She gives him books.
Because English verbs have free valence, and there is no necessary relationship between a verb subject and the agent, English allows the formation of sentences that some other languages would resist. The verb subject may stand in several different case relationships to the topic:
Instrumental: That book will make us a million dollars. cf. We will make a million dollars with that book.
Origin: The dam is leaking water. cf. Water is leaking from the dam.
Location: The forest rustles with dead leaves. cf. Dead leaves rustle in the forest.
Topical: This construction project cannot proceed. cf. "We cannot proceed with this construction project."
English does not allow pronoun dropping, and all verbs must have an explicit subject, even where there is no specific agent. Dummy pronouns are inserted even where no agent is identifiable: It is raining. Even sentences that declare the existence of something require a deictic particle to be well formed in English:
There is a river. This is a lake.
The deixis relates to the tense of the verb. "There" is the default, unmarked particle; "here" is also possible, but does imply proximity to the speaker:
There is a river Here is a river
The past is remote by definition. There was a river is normal; but *here was a river is unusual: it either represents poetic diction, or suggests that the river that once was here is no longer present. A regular English verb has only one principal part, the infinitive or dictionary form (which is identical to the simple present tense for all persons and numbers except the third person singular). All other forms of a regular verb can be derived straightforwardly from the infinitive, for a total of four forms (e.g. exist, exists, existed, existing).