Two word sentences are a form of

If «sentence» means a chunk of writing that begins with a capital letter and ends with a period, then the answer is yes. What you’ve written is not «bad» or «wrong.» It’s something people do for rhetorical effect, such as to sound dramatic. In genres like creative writing, fiction, or just informal writing in general, you can do things like that.

If «sentence» means what sentence usually means, the answer is still «yes»—but the two-word things that you’ve written here are not sentences; they’re noun phrases. For that reason, if this was in a paper that was being graded, the instructor MIGHT dislike them. If the instructor dislikes them, he/she will probably call them «fragments». Sentences usually have a subject (something doing the action or that the sentence is about) and a predicate (what the subject is doing or more information about the subject). Examples of two-word sentences that everyone would agree are «complete sentences» are «Dogs bark» (Subject Verb), «I slept» (Subject Verb), and «We left» (Subject Verb).

If «sentence» means «utterance» or «turn at speaking,» the answer is also «yes». We can even have one-word utterances, like «Yes» or «Goodbye.»

In other words, the sample of your writing that you’ve shared sounds perfectly fine, but not everyone would refer your two-word things as «sentences»—and SOME instructors might circle them with a red pen and call them «fragments».

Additional information to the §3 — §4 pages 224 -225

Two-member and one-member sentences. One-member and elliptical
sentences. Two approaches. Types of elliptical sentences.

Two-member sentences

§ 1. 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.

4.
John learned French.

5.
John gives Mary his books. in London.

6.
John lives there

7.
We found John guilty.

8.
We found John a bore.

The
basic pattern may be unextended or extended.

An
unextended sentence contains two main positions of the basic pattern, that of
the subject and the predicate.

1.
Mary laughed.

2.
Mary is a doctor.

3.
Mary is happy.

An
extended sentence may contain
various optional elements (including
attributes, certain kinds of prepositional objects and adverbial modifiers).

1.John
ran quickly to me.

2.My
friend John is a very kind student.

3.Mary
laughed heartily at the joke.

Obligatory
extending elements are those which complete the meaning of other words, usually
verbs, or pronouns, which without them make no or little sense. Therefore,
obligatory elements are called complements.

1.John
learned French. (the meaning of «learned» is incomplete without the
object «French»)

2.John
gives Mary his books. (the meaning of «gives Mary» conveys a
different meaning without the object «his books»)

3.John
lives in London. (the meaning of «lives» is incomplete without an
adverbial of place)

One-member sentences

§
4. 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)   
extended.

Dusk — of a
summer night.

The grass,
this good, soft, lush grass.

English
spring flowers!

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.

1.To
think of that!

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

3.Living
at the mercy of a woman!

Elliptical (incomplete) sentences

§
5. 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.

Don’t know
anything about it.

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.

Susan’s
father?

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?

You sure?

All settled.

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.

What do you
want of us? Miracles?

Where’re you
going? — Home.

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.Источник: http://5fan.ru/wievjob.php?id=46848

Many common words and phrases are identical except for a strategic letter space — apart and “a part” come to mind — and though knowing which form to use in a sentence is often obvious (as in that example), the difference can be subtle. Here are some of the less clear-cut pairs:

1. Ahold/a hold: Ahold is a variant of the noun hold, used in such sentences as “I’ll get ahold of you later.” But when you mean to refer to an actual grip on something, use two words: “She really has a hold on you.” If it’s hard to decide which form to employ, try this test: If you can insert an adjective between a and hold, the two-word form is appropriate.

2. Already/all ready: Use the former when you need an adverb, as in “I told you already.” The latter form is correct in sentences such as “We’re all ready for the party.”

3. Alot/a lot: These two forms are interchangeable except in one significant respect: The one-word version is wrong. It is used often in informal writing and may one day be standard, but until you get the official memo, refrain from using it if you want to be taken seriously as a writer.

4. Alright/all right: See item number 3.

5. Altogether/all together: The one-word form, an adverb, suffices to mean “completely” or “in total,” as in “Altogether, we saved $100 on the deal.” (It also means “nude” in the idiomatic phrase “in the altogether.”) The phrase is appropriate for sentences such as “We are all together in this.”

6. Anybody/any body: The one-word form is a pronoun used in such constructions as “He doesn’t get along with anybody.” The two-word adjective-noun form is applicable in limited contexts, such as in the sentence “Any body in motion responds to gravity.”

7. Anymore/any more: The one-word form is used as an adverb in sentences such as “We don’t go there anymore”; the two-word form consists of the adjective any and the noun more, as in “I just can’t eat any more of that pie.”

8. Anyone/any one: The one-word form is a pronoun, synonymous with anybody, used as in “Anyone can make that claim.” “Any one” consists of the adjective any and the noun one, as in “Any one of you might be next.”

9. Anyplace/any place: The adverb anyplace is a synonym for anywhere: “She won’t let me go anyplace without her.” The latter usage is an adjective-and-noun phrase that describes a location: “He doesn’t want to go to any place he can’t smoke.”

10. Anything/any thing: Anything is the likely usage: “I don’t remember anything.” The two-word adjective-noun form is generally separated by an another adjective: “She’s just does any little thing she wants.”

11. Anytime/any time: To describe with what frequency something might occur, use the one-word adverbial form: “Stop by anytime.” The two-word adjective-noun form is preceded by the word at: “You may leave at any time.”

12. Anyway/any way: Anyway is a synonym for anyhow: “We didn’t want to go anyway.” The two-word adjective-noun form is preceded by the word in: “That doesn’t change the results in any way.”

13. Awhile/a while: The noun phrase “a while” and the adverb awhile are virtually interchangeable in a sentence, though you should precede the two-word form with the word for: “I think I’ll sit here for a while” and “I think I’ll sit here awhile” mean the same thing.

14. Cannot/can not: Cannot is virtually the only proper alternative. The second usage is wrong except in the correct awkward construction in the sentence “I can not go,” meaning “I can decide not to go.”

15. Everyday/every day: The one-word form is an adjective meaning “ordinary,” used to describe something usual as in “These are my everyday clothes.” The two-word phrase, an adverb, is used in such sentences as “I go there every day” to explain how something is done.

16. Everyone/every one: To refer to everybody, use one word: “Everyone’s a critic.” To emphasize a single individual or item, use two words: “Every one of them is broken.”

17. Everything/every thing: Everything is the default choice: “You’ve ruined everything.” The two-word adjective-noun form is usually divided by an additional adjective: “Every little thing she does is magic.”

18. Maybe/may be: The first choice is an alternative to the adverb perhaps; the second is a verb phrase used in such sentences as “It may be that she was right after all.”

19. Overtime/over time: As one word, this means work done beyond a regular shift: “I’ve worked overtime several days this week.” As two words, it refers to the passage of time: “Over time, we’ve seen dramatic changes.”

20. Sometime/some time: The one-word form is an adverb describing vagueness about when something will happen, as in “I’ll get around to it sometime.”

What is syntax?

• Syntax is the study of the structure of sentences.

• Syntax analyzes how words combine to form sentences.

• Sentences are made up of smaller units, called phrases (which in turn are made up of words).

Why is syntax important?

• We speak in sentences not in words. To understand the structure of a language it is necessary to study the structure of sentences.

• If we learn to analyze the structure of sentences, we will also learn to analyze their meaning.

• The study of syntax is the study of the function of words, which is necessary to understand the structure and the meaning of a language.

The basic functions

• Subject: obligatory element; it specifies the entity about which we will say something (the doer of the action, the entity described, etc.)

• Object: obligatory element, it completes the meaning of a word or sentence.

• Subject or Object Complement: obligatory element that adds a description of the subject or the object. These function also receive the names of Attribute and Predicative.

• Modifier: optional element; adds additional information that specifies a noun

• Adverbial: optional element; modifies a verb, adjective or adverb

What is a sentence?

Although everyone knows or thinks they know what a word is and what a sentence is, both terms defy exact definition. The sentence as a linguistic concept has been defined in over 200 different ways, none of them completely adequate. Here are the most important attempts at defining the sentence:

The traditional, or common sense definition states that a sentence is a group of words that expresses a thought . The problem comes in defining what a thought is. The phrase an egg expresses a thought but is it a sentence? A sentence like I closed the door because it was cold expresses two thoughts and yet it is one sentence.

• A sentence is basically a string of words that follow the grammatical rules of a language.

• A sentence expresses a complete thought

• A sentence is made up of phrases. At the very least a sentence contains a verb phrase (also known as the predicate) and a subject.

• We will use the terms SENTENCE and CLAUSE indistinctively.

What is a phrase?

• A phrase is a part of a sentence. It does not express a complete thought.

• A phrase is a group of words that function as a single unit. Usually they can be substituted by a pronominal form.

• All phrases have one word which is the nucleus, the head. The head of a phrase determines the kind of phrase we have: Noun Phrase, Adjective Phrase, Adverb Phrase, Prepositional Phrase or Verb Phrase.

A phrase is a small group of words that forms a meaningful unit within a clause. 

A clause is a group of words that contains a verb (and usually other components too). A clause may form part of a sentence or it may be a complete sentence in itself.

A sentence is a group of words that makes complete sense, contains a main verb, and begins with a capital letter.

Sentence must:

• have a subject and a verb (predicate)

• MUST have a complete though

• Begins with a capital letter

• Ends with punctuation

• have intonation

Sentences are used:

• to make statements:

• to ask questions or make requests:

• to give orders:

• to express exclamations:

Syntactic atoms

• The basic unit of syntax is not the word, but the syntactic atom, defined as a structure that fulfills a basic syntactic function. Syntactic atoms may be either a single word or a phrase that fulfills a single syntactic function.

• Fido ate the bone.

• The dog ate the bone.

• The big yellow dog ate the bone.

• Our dog that we raised from a puppy ate the bone.

Simple sentence

A simple sentence normally contains one statement (known as a main clause). For example:

The train should be here soon.

His father worked as a journalist.

Compound sentence

Joe became bored with teaching	and	he looked for a new career.
[main clause]	[conjunction]	[main clause]

Boxers can be very friendly dogs	but	they need to be trained.
[main clause]	[conjunction]	[main clause]

Complex sentence

The story would make headlines	if it ever became public.
[main clause]	[subordinate clause]
He took up the project again	as soon as he felt well enough.
[main clause]	[subordinate clause]

A clause is a group of words that contains a verb (and usually other components too). A clause may form part of a sentence or it may be a complete sentence in itself. For example:

He was eating a bacon sandwich.

[clause]

She had a long career	but she is remembered mainly for one early work.
[clause]	[clause]

Main clause

Every sentence contains at least one main clause. A main clause may form part of a compound sentence or a complex sentence, but it also makes sense on its own, as in this example:

He was eating a bacon sandwich.

[main clause]

Compound sentences are made up of two or more main clauses linked by a conjunction such asand, but, or so, as in the following examples:

I love sport	and	I’m captain of the local football team.
[main clause]	[conjunction]	[main clause]

She was born in Spain	but	her mother is Polish.
[main clause]	[conjunction]	[main clause]

Subordinate clause

A subordinate clause depends on a main clause for its meaning. Together with a main clause, a subordinate clause forms part of a complex sentence. Here are two examples of sentences containing subordinate clauses:

After we had had lunch,	we went back to work.
[subordinate clause]	[main clause]

I first saw her in Paris,	where I lived in the early nineties.
[main clause]	[subordinate clause]

A phrase is a small group of words that forms a meaningful unit within a clause. 

Types of Syntactic Relations

One of the most important problems of syntax is the classification and criteria of

distinguishing of different types of syntactical connection.

L. Barkhudarov (3) distinguishes three basic types of syntactical bond:

• subordination,

• co-ordination,

• predication.

Subordination implies the relation of head-word and adjunct-word, as e.g. a tall boy, a red pen and so on.

The criteria for identification of head-word and adjunct is the substitution test. Example:

1) A tall boy came in.

2) A boy came in.

3) Tall came in.

This shows that the head-word is «a boy» while «tall» is adjunct, since the sentence (3) is

unmarked from the English language view point. While sentence (2) is marked as it has an invariant meaning with the sentence (1).

Co-ordination is shown either by word-order only, or by the use of form-words:

4) Pens and pencils were purchased.

5) Pens were purchased.

6) Pencils were purchased.

Since both (5), (6) sentences show identical meaning we may say that these two words are

independent: coordination is proved.

Predication is the connection between the subject and the predicate of a sentence. In predication none of the components can be omitted which is the characteristic feature of this type of connection, as e.g.

7) He came …

*He …

9) * … came or

10) I knew he had come

11) * I knew he

12) * I knew had come

Sentences (8), (9) and (11), (12) are unmarked ones.

H. Sweet (42) distinguishes two types of relations between words: subordination, coordination.

Subordination is divided in its turn into concord when head and adjunct words have alike inflection, as it is in phrases this pen or these pens: and government when a word assumes a certain grammatical form through being associated with another word:

13) I see him, here «him» is in the objective case-form.

The transitive verbs require the personal pronouns in this case.

14) I thought of him. “him” in this sentence is governed by the preposition “of”. Thus, “see” and “of” are the words that governs while “him” is a governed word.

B. Ilyish (15) also distinguishes two types of relations between words: agreement by which he means «a method of expressing a syntactical relationship, which consists in making the subordinate word take a form similar to that of the word to which it is subordinated». Further he states: «the sphere of agreement in Modern English is

extremely small. It is restricted to two pronouns-this and that …» government («we understand the use of a certain form of the subordinate word required by its head word, but not coinciding with the form of the head word itself-that is the difference between agreement and government»)

e.g. Whom do you see

This approach is very close to Sweet’s conception.

As one can see that when speaking about syntactic relations between words we mention the terms coordination, subordination, predication, agreement and government

It seems that it is very important to differentiate the first three terms (coordination, subordination and predication) from the terms agreement and government, because the first three terms define the types of syntactical relations from the standpoint of dependence of the components while the second ones define the syntactic relations from the point of view of the correspondence of the grammatical forms of their components. Agreement and government deals with only subordination and has nothing to do with coordination and predication. Besides agreement and government there is one more type of syntactical relations which may be called collocation when head and adjunct words are connected with each-other not by formal grammatical means (as it is the case with agreement and government but by means of mere collocation, by the order of words and by their meaning as for example: fast food, great day, sat silently and so on).

subordination – подчинение

coordination –согласованность

predication – предикация

agreement- согласование

Согласование (agreement) имеет место тогда, когда подчиненное слово принимают форму, сходную с формой ядерного слова, например: this boy, these boys; the child plays, the children play; в английском языке слова согласуются только по категории числа в некоторых контекстах.

Управление (government) имеет место тогда, когда некая форма адъюнкта требуется при присоединении к ядерному слову, но не совпадает с ним по форме, например: to see him; to talk to him. Rely on him, to be proud of her.

Примыкание(adjoinment)- не предполагает никакого формального признака связи, слова объединяются просто на основе контакта друг с другом, например: to go home, to nod silently, to act cautuiosly.

Замыкание(enclosure) имеет место тогда, когда адъюнкт располагается между двумя частями аналитической формы ядерного слова, например: to thoroughly think over, the then government, an interesting question , a pretty face, your pretty man, on good essay.

Theme and Rheme

Theme-functions as the ‘starting point for the message’ (M. A. K. Halliday, 1985a, p. 39),the element which the clause is going to be ‘about’ has a crucial effect in orienting listeners and readers. Theme is the starting point of the clause, realised by whatever element comes first.

Rheme

is the rest of the message, which provides the additional information added to the starting point and which is available for subsequent development in the text. The different choice of Theme has contributed to a different meaning and English uses firstclausal position as a signal to orient a different meaning of the sentences. For example,

 Li Ping read a very good book last night.

Li Ping— theme

read a very good book last night.- rheme

 A very good book,Li ping read last night.

A very good book— theme

Li ping read last night.- rheme

 Last night  Li ping read a very good book.

What Li Ping read 

Last night was a very good book.

 Li Ping,he read a very good book last night.

In each case above, the writer starts the message from a different point, that is, to choose a different Theme for the clause. As Halliday (1994, p.38) mentioned Theme as the‘starting-point for the message’ or ‘the ground from which the clause is taking off’.

And also, the different choice of Theme has contributed to a different meaning. What makes these sentences different is that they differ in their choice of theme and they tell us what

 Li Ping, Avery good book, Last night or What Li Ping read 

is going to be about.