We can all speak and understand each other; do we need to investigate how?

Two-member sentences:

The magpie flew off.

We are going to my house now.


One-member sentences:

An old park.

Mid-summer.
Low tide, dusty water.
To live alone in this abandoned house!

Chapter 2 THE SIMPLE SENTENCE

2.1 Two-member sentences

The basic pattern of a simple sentence in English is one subject-predicate unit, that is, it has two main (principal) positions: those of the subject and of the predicate. It is the pattern of a two-member sentence. There are several variations of this basic pattern, depending mainly on the kind of verb occupying the predicate position. The verb in the predicate position may be intransitive, transitive, ditransitive or a link verb.

Here are the main variants of the fundamental (basic) pattern:
1. John ran.
2. John is a student.
3. John is clever.

2.2 One-member sentences

One-member sentences in English are of two types: nominal sentences and verbal sentences.
Nominal sentences are those in which the principal part is expressed by a noun. They state the existence of the things expressed by them. They are typical of descriptions.
Nominal sentences may be:

a) unextended.

Silence. Summer. Midnight.
b) e x t e n d e d.
Dusk - of a summer night.
Verbal sentences are those in which the principal part is expressed by a non-finite form of the verb, either an infinitive or a gerund. Infinitive and gerundial one-member sentences are mostly used to describe different emotional perceptions of reality.

To think of that!

To think that he should have met her again in this way!

2.3 Elliptical (incomplete) sentences

A two-member sentence may be either complete or incomplete (elliptical). An elliptical sentence is a sentence in which one or more word-forms in the principal positions are omitted. Ellipsis here refers only to the structural elements of the sentence, not the informational ones. This means that those words can be omitted, because they have only grammatical, structural relevance, and do not carry any new relevant information.
In English elliptical sentences are only those having no word-forms in the subject and predicate positions, i. e., in the positions which constitute the structural core of the sentence.
There are several types of elliptical sentences.
1. Sentences without a word-form in the subject position.
Looks like rain.
Seems difficult.
2. Sentences without word-forms in the subject position and part of the predicate position. In such cases the omitted part of the predicate may be either a) an auxiliary verb or b) a link verb.
a) Going home soon?
See what I mean?
Heard nothing about him lately.
b) Not bad.
Free this evening?
Nice of you to come.
3. Sentences without a word-form only in part of the predicate position, which may be an auxiliary or a link verb.
You seen them?
Everything fixed?
4. Sentences without word-forms both in the subject and the predicate position. Such ellipses occur in various responses.
What time does Dave come for lunch? - One o’clock.
What were you thinking about? - You.
5. Sentences without a word-form in the predicate position. Such ellipses occur only in replies to questions.
Who lives there? - Jack.
What’s happened? - Nothing.