Form and Function of the English Clause

Grammar: Words and Their Arrangement

Form and Function of the English Clause

A sentence is a sound in itself on which other sounds called words are strung.

Robert Frost, Selected Letters

The word "grammar" has many meanings. For some people, grammar specifies the "correct" way to speak or write. For others, the word refers to the inflections (the word endings) common in many languages. For still others, the grammar is about how humans organize ideas into words. The word "grammar" means all of those things. But, for us, the word means something quite specific: grammar describes how we choose and arrange our words.

Yet grammar is more than passively learning ideas about the organization of words in a language. Grammar is also an activity; it is something we do. For example, consider this paragraph from the opening of Anthony Burgess's A Clockwork Orange.

There was me, that is Alex, and my three droogs, that is Pete, Georgie, and Dim, Dim being really dim, and we sat in the Korova Milkbar making up our rassoodocks what to do with the evening, a flip dark chill winter bastard though dry. The Korova Milkbar was a milk-plus mesto, and you may, O my brother, have forgotten what these mestos were like things changing so skorry these days and everybody very quick to forget, newspaper not being read much neither. Well, what they sold there was milk plus something else. They had no license for selling liquor, but there was no law yet against prodding some of the new veshches which they would put into the old moloko, so you could peet it with vellocet or synthemesc or drencrom or one or two other veshches which would give you a nice quiet horrorshow fifteen minutes admiring Bog And All His Holy Angels And Saints in your left shoe with lights bursting all over your mozg. Or you could peet it with knives in it, as we use to say, and this would sharpen you up and make you ready for a bit of dirty twenty-to-one, and that was what we were peeting this evening I'm starting off the story with.

As you read the paragraph above, your thinking probably went through several stages: first, you noticed the unusual words and felt a certain uneasiness about the language; it seemed to be English, but not quite right. Then, you probably noticed that several of the unusual words had ending that you recognized or were surrounded by familiar words. Finally, having guessed at the meaning of those unusual words from context clues in that paragraph, you could reread the paragraph more easily. In other words, you were acting as a grammarian already: you

• observed the language data (by noticing the unusual words in their contexts),
• collected a few pertinent facts (by noticing that several words were placed near function words like the or of and by noticing word endings like -s or -ing, clues to how the strange words functioned in those clauses),
• made and tested a hypothesis (by rereading a sentence after revising mentally to add the information you collected by noticing the word's position and endings), and
• reached a conclusion (that your hypothesis was correct because the paragraph made more sense).

In short, those are the same steps any linguist takes when studying any phenomenon in language, including grammar.

Furthermore, understanding that paragraph from A Clockwork Orange means understanding (at least at some level) and using all the fundamental concepts of grammar: categories, constituency, and metafunctions. The concept of category allows us to recognize that several of the unfamiliar words belong to the word category 'noun.' Another concept, constituency, allows us to recognize that several unusual sequences of words in the first paragraph (such as Bog And All His Holy Angels And Saints or Korova Milkbar) must be single units, despite the fact that they are odd sequences of words. Finally, through a concept of metafunction, we are able to recognize several additional facts about that paragraph: even though the words are unusual for English, the sentences are statements (rather than question or commands); moreover, the 'theme' of paragraph is largely about Alex's perceptions about milkbars, particularly the Korova Milkbar.

Yet before we begin to explore more examples of the grammar of human language at work, let's first settle some initial concerns: what does 'grammar' mean and what is the place of grammar in the structure of language as a whole?

SOME PRELIMINARIES

Grammar is about how units of language are sequenced, since quite obviously language proceeds sequentially, linearly: in speech, one sound is uttered before the next, one syllable before the next, one word before the next, and so on; in writing, one word precedes the next, one phrase precedes the next, one clause precedes the next, and so on. So at some point in the production (and the same is true in the inverse for the perception) of language, humans must take all their thoughts, requests, desires, and hopes that are relevant within a particular context of situation and produce language that expresses those meanings and organizes those ideas sequentially. The same is true in the inverse for the perception of language.

Now one might quite rightly ask doesn't the word 'grammar' alone suggest some sequential arrangement of linguistic units? Yes, the idea of grammar (both in its popular and in several of its technical senses) does emphasize the importance of the right sequence of words, phrases, and clauses within a sentence. However, there are many reasons why those of us who are fascinated by language and interested in accurately describing and explaining how language works should pay close attention to words in grammar. For our purposes here, we will discuss only two.

First, if we were to ask people what they thought were the fundamental building blocks of language, they would very likely say "Words" more than any other response (with "syllable" the only real competition). Words seem to be the most obvious component of language, and any theory that fails to account for the contribution of words to the functioning of language is unworthy of our attention. (See Halliday 1994.) So for that reason alone we need to include words in our study of grammar. Moreover, there are many other, less obvious, reasons why we need to attend to words in our grammatical description.

To illustrate this second reason for the importance of words in our description of grammar, consider sentences (1) through (4):

1. The water evaporated.
2. The dog evaporated.
3. The water evaporated quickly.
4. The water evaporated the dog.

Sentences (1) through (4) illustrate that the word evaporate is restricted in its usage in quite specific ways. But if we had only to work with a grammar of English that examines grammatical structures without referring to the lexicon, we would quickly discover the weakness of our grammatical analysis. For example, looking at the structure of the sentences in (1) through (4), we see some really quite ordinary arrangements of clause elements, arrangements that occur regularly in English. In (1) and (2), we have the Subject-Verb (SV) pattern; in (3) we see the Subject-Verb-Adverbial (SVA) pattern; in (4) we find the Subject-Verb-Object (SVO) pattern. Now a grammar that ignores the lexicon will describe all the sentences in (1) through (4) as well-formed structures (since they are after all very common clause patterns), only to realize the inadequacy of such a description and propose some kind of remedy to the problem elsewhere in the theory.

However, if the theory incorporates into its grammar all the meaningful distinctions found in the lexicon, then there need be no division between the grammatical and lexical 'levels' in our analysis of language. In our example, in other words, our grammar will be sensitive to the fact that in real language, we must distinguish between transitive (verbs that can occur with an object in an SVO pattern) and intransitive (verbs that may not occur with an object, but may occur with some other complement, such as an adverbial, as in the SV and SVA patterns) early on in our description of the language. Thus, by recognizing that some forms function as intransitive verbs, we can explain why (4) seems so peculiar, while (1) and (3) seem quite ordinary. Further, if our description of the language — our grammar that is — also recognizes the distinction between verbs that can co-occur with 'agent' subjects as opposed to those verbs that do not, then we can explain why (2) seems odd.

Now that we have some sense of why the lexicon contributes so substantially to our understanding of a language's grammar, we may go on to consider grammar's place in the structure of language. Halliday posits four strata at work, simultaneously, in the production and perception of language:

• the context of the language situation
• meaning (semantics)
• wording (grammar)
• sound patterns (phonology and phonetics)

To illustrate how the different levels of language co-exist, consider the odd examples of sentences (2) and (4) again. Given our conventional world as the context for the language situation we are in at this moment, sentences like (2) and (4) do seem strange since they suggest ideas that we recognize as unlikely. But, if we changed the context of situation to that of science fiction, suddenly sentences like (2) and (4) make sense. Assuming some alternate universe where our laws of physics are pushed beyond our experience or altogether void, sentences (2) and (4) are meaningful.

For another example, consider these sets of contexts and sentences: all four sentences are requests for an open window from the speaker to a listener. However, the context of situation is different for each sentence. Which sentence goes with which situation below?

	Sentence		Situation
(a)	Pardon me, sir, but would you mind opening the window?	(i)	Doing homework with your girl-/boyfriend.
(b)	Open the window, will ya buddy?	(ii)	Baby-sitting your snotty younger brother.
(c)	Open the window NOW.	(iii)	Meeting with the dean in his office.
(d)	Gee, it's hot in here.	(iv)	Sitting on a bus next to a man dressed in work clothes.

If you found that you could match (a) with (iii), (b) with (iv), (c) with (ii), and (d) with (i), then you were experiencing how context, meaning, and wording all mutually interact in language.

In (a), notice that the context of situation (meeting with the dean in his office) places us in a socially less powerful position. After all, we are in his office; we are not on his social/political level. Therefore, when we make a request of someone 'above' us on some social scale, notice how the meaning and the wording (grammar) change: the request is not in the form of a command, but more politely put in the form of a question. Yet even though the grammar of (a) is the form of a question that could be answered by yes or no, we do not mean it to be interpreted as a question, nor do we expect it to be interpreted by the dean as a yes/no question. (Indeed, if the dean answered "No," we could most likely interpret the response as either an attempt at humor or an act of hostility.) Other markers of politeness in (a) are the speaker's request for permission to speak (Pardon me) and the vocative (sir).

In (b) and (c), we find two forms that are commands. We can distinguish them and match their contexts because of the differing markers of politeness in each. In (b), the tag question at the end of the command undercuts the forcefulness of the command, as does the familiar term of address (buddy) and the informal pronunciation of the pronoun you. Those features of grammar point to a situation in which one is probably speaking to a stranger in a close situation. In (c), however, one finds the same command ending with a heavily stressed time adverbial, highlighting through the grammar the forcefulness of the command and the speaker's social power.

In (d), we have another form that is not a command at all grammatically: it is a statement. But notice that it begins with a word to indicate the speaker's discomfort (Gee), and notice that the word hot is ambiguous in this context, possibly referring either to the speaker's temperature or the speaker's excitement in this context.

In (a) through (d), we can see, therefore, that the context of situation, the meaning, the grammar, and even the sound patterns mutually interact to create the language we use. But notice in those examples that the choices of wording (grammar) do not simply encode meaning: rather, the grammar makes meaning. That distinction is fundamental between this theory of language (systemics) and other theories of grammar.

To understand more about grammar, we must now examine the grammatical constituents of language (categories), how those constituents combine at different levels (constituency), and how those combinations of constituents can create meaning (metafunction).

Form and Function of the Clause in English

Words and phrases are the constituents of the clause rank. In order to discuss the constituents of the clause, it is necessary to refer to the units smaller than the clause itself. Consider the following example, in which we can see that a single clause is composed of smaller units of the phrase rank.

From our discussion of the phrase rank, we also know that we can categorize the constituents of that clause into the appropriate phrase type.

Furthermore, we also know that each phrase can be subcategorized into its constituent parts.

The diagram above, however, looks at the constituents of the clause only from the perspective of the constituents' forms. We should remember that those forms also serve functions, just as the forms at the phrase rank can also be described according to the functions they served within their phrases. Essentially the clause can be divided into eight functional constituents, grouped into five categories:

Functional Categories	Eight Clause Functions
(1) Subject	[1] Subject
(2) Verb	[2] Verb
(3) Objects	[3] Direct Object
	[4] Indirect Object
(4) Complements	[5] Object Complement
	[6] Subject Complement
(5) Adverbials	[7] Adverbial Complement
	[8] Adverbial

At the clause rank, the constituents marked in the example sentence above serve four different clause functions: subject (S) as in The news, verb (V) as in has been, subject complement (SC) as in quite sad, and adverbial (A) as in in fact. We use the following abbreviations for the other four clause functions: direct object (DO), indirect object (IO), object complement (OC), and adverbial complement (AC). The examples below illustrates some other clause patterns that are possible in English.

1. Liz (S) is resting (V) quietly (A) in the other room (A).
2. The mind (S) is (V) immensely complex (SC).
3. The children (S) were (V) here (AC) all morning (A).
4. Emily (S) is playing (V) cards (O) with her sister (A).
5. Early next week (A), the President (S) will send (V) Congress (IO) his budget (DO).
6. Clearly (A), the committee (S) considers (V) her (DO) the best (OC).
7. Once again (A), I (S) will put (V) the book (DO) away (AC).

When we look at the examples, we notice that each clause has a different arrangement of functional elements, but there are some patterns too. First, we notice that while the different clauses have different arrangements of objects, complements, and adverbials, each clause consistently has a subject and verb. Thus, in the declarative clause, we call the functions of subject and verb the 'central' functions while objects, complements, and adverbials are the 'peripheral' functions. We also notice that adverbials are 'optional' when compared to the other clause constituents. That is, we could easily eliminate all the adverbials in sentences (1) through (7) and still have a well-formed English clause remaining. By eliminating the optional adverbials, then, we arrive at a classification of the basic clause patterns on the basis of the 'obligatory' constituents.

Some Examples of the Seven Clause Patterns in English
	S	V	IO	DO	SC	OC	AC
SV	Liz	is resting
SVC	The mind	is			complex
SVA	The kids	were					here
SVO	Emily	is playing		cards
SVOO	Clinton	will send	Congress	his budget
SVOC	We	consider		her		the best
SVOA	I	will put		the book			away

This set of patterns is the most general classification that can be usefully applied to the English clause. Correlating with the seven clause patterns are the three main types of verbs:

• intransitive verbs, followed by no obligatory constituents, as in SV pattern above;
• copular verbs, followed by a SC or AC, as in the SVC and SVA patterns above; and
• transitive verbs, followed by an object, as in the SVO, SVOO, SVOC, and SVOA patterns above.

To conclude this outline of the basic clause patterns, we need to understand the principles by which the functional constituents of the clause are identified. Although the categories of S, V, DO, IO, OC, SC, AC, and A are functional constituents, they are identifiable by both formal and functional criteria.

The Subject

The subject, like the verb, is a central constituent in the clause. And as a central element, it 'governs' many of the grammatical choices to be made within the clause. The subject determines agreement between itself and the verb and governs the person, number, case, and gender, where relevant, of several other constituents within the clause. Traditional grammar books and school grammars often define the subject along semantic lines: they refer to the subject as "what the sentence is about" or as "the topic of the sentence" or as the "actor performing the action described by the verb. From the perspective of grammar, however, such definitions are misleading, since those older definitions blend and conflate different ideas that are best understood if kept apart. As we will see soon in the section on METAFUNCTION, the subject is a distinct entity, related to, but separate from, notions like 'theme' or 'topic' or 'actor.'

Grammatical subjects usually share a number of properties that serve to identify them within a clause. These are form, position, agreement, pronouns, and voice.

Form. The subject is usually a noun phrase or clause.

That guy (S) is the one.

What I don't know (S) can hurt me.

Position. The subject is usually positioned before the verb in the indicative mood, after the auxiliary in the interrogative mood, and absent — but implied — in the imperative mood.

Sandy (S) fell asleep. [indicative mood]

Did I (S) win? [interrogative mood]

Go home! [imperative mood]

Agreement. Subjects usually determine the number (singular or plural) and person (first, second, third) of other constituents in the clause. The subject determines the number and person, where relevant, of the verb in finite clauses.

Liz (S) works (V) hard. [singular, third person]

Emily and Liz (S) work (V) hard. [Plural]

The subject determines the number and person, where relevant, of any noun phrase functioning as the subject complement.

Frank (S) is my nephew (SC)

Frank, Mike, and Paul (S) are my nephews (SC)

The subject also determines the number, person, and gender, where relevant, of 'reflexive' pronouns — pronouns ending with the -self or -selves inflections.

I (S) cut myself.

They (S) cut themselves.

The subject determines the number, person, and gender, where relevant, of the emphatic pronoun own in structures such as my own or their own.

I (S) cut myself with my own knife.

They (S) cut themselves with their own knives.

Pronouns. The subject determines the case, where relevant, of any pronoun in subject function; that is, the subject function requires the subjective form of the pronoun.

I (S) like her.

She (S) likes me.

Voice. There is a systematic relationship between the subject of a clause and voice (active or passive). The active voice subject corresponds to an adverbial (beginning with the preposition by) in the passive voice.

Emily (S) likes Liz. [active voice]

Liz is liked by Emily (A) [passive voice].

The Verb

The function of verb is the least ambiguous in English since only one category (the verb phrase) fills this function. Nonetheless, the verb is recognizable by a combination of formal and functional properties. These are form, position, agreement, tense, modality, aspect, and voice.

Form. The verb is composed of a main verb with or without auxiliaries.

Frank reads (V) quickly.

Frank must have been reading (V) quickly.

Position. The verb usually occurs after the subject in the indicative mood, around the subject in the interrogative mood, and at the beginning of the clause in the imperative mood.

Sandy fell (V) asleep. [indicative mood]

Did I win (V)? [interrogative mood]

Go (V) home! [imperative mood]

Agreement. The verb corresponds in number (singular or plural) with the subject in finite clauses.

Liz (S) works (V) hard. [singular, third person]

Emily and Liz (S) work (V) hard. [plural]

Tense. The verb of a finite clause is marked for tense (present or past).

Mike likes (V) Nintendo. [present]

Mike liked (V) Nintendo. [past]

Modality. The verb can be marked as predicating something other than simple fact (modal).

Paul might do (V) it. [modal]

Paul ought to do (V) it. [semi-modal]

Aspect. The verb can be marked as completing or continuing the process indicated by the main verb (perfect and/or progressive).

Paul has done (V) it. [perfect]

Paul is doing (V) it. [progressive]

Paul has been doing (V) it for a long time. [perfect and progressive]

Voice. The verb is marked for voice (active or passive).

Emily likes (V) Liz. [active voice]

Liz is liked (V) by Emily. [passive voice]

The Direct Object

The direct object is identifiable by its formal and functional properties. These are form, position, pronouns, and voice.

Form. The direct object usually has the form of a noun phrase or clause.

The cat chased the mouse (DO).

I know that she will be here soon (DO).

Position. Direct objects usually occur after the subject and verb, as in the examples above.

Pronouns. If the subject and the object of a clause refer to the same entity, then the object will be in the form of a reflexive pronoun. The reflexive pronoun will agree with the subject in number, person, and gender, where relevant.

You (S) should see yourself (DO).

We (S) rewarded ourselves (DO) with a treat.

All other pronouns assuming object function will take the objective form.

I like her (DO).

She likes me (DO).

Voice. There is also a systematic relationship between the object of an active voice clause and the subject of a passive voice clause. The object of the active voice clause corresponds to the subject in the passive voice equivalent.

Emily likes Liz (DO). [active voice]

Liz (S) is liked by Emily [passive voice]

The Indirect Object

The indirect object is identifiable by all of the criteria of the direct object with a few unique characteristics of its own in form and position.

Form. Although both objects usually occur either as noun phrases or as clauses in form, the indirect object is restricted to the relative clause form.

I sent whoever wants it (IO) copies of a receipt.

Position. The indirect object can occur only when the direct object is also represented in the clause. (Here we use the asterisk [*] to represent ungrammatical forms in a language.)

We gave her (IO) everything (DO).

*We gave her (IO).

The indirect object also occurs only between the verb and the direct object.

We gave (V) her (IO) everything (DO).

*We gave (V) everything (DO) her (IO).

Moreover, only the indirect object can be paraphrased by a prepositional phrase functioning as an adverbial, beginning with either to or for. The choice of the preposition is governed by the main verb of the clause.

We gave her (IO) everything (DO).

We gave everything (DO) to her (A).

Finally, the indirect object can be omitted without affecting the semantic relationships of the remaining constituents of the clause.

We (S) gave (V) her (IO) everything (DO).

We (S) gave (V) everything (DO).

The Object Complement

The object complement completes a reference and/or an implication suggested by the object of the clause. The object complement is identifiable by its form, position, reference, and agreement.

Form. Object complements are most usually noun phrases or adjective phrases, although a clause may assume this function on occasion.

They elected her Chair of the department (OC).

We find this music most pleasant (OC).

Position. Object complements only occur if there is an object in the clause and then occur normally after that object.

They elected her Chair of the department (OC).

*They elected Chair of the department (OC).

*They elected Chair of the department (OC) her.

And unlike objects themselves, object complements do not have any passive voice corresponding clauses, in which the complement appears in the subject position.

*Chair of the department was elected her by them.

Reference. Since all complements imply a reference, object complements complete a reference to the object of the clause. There is in effect a copular relation that exists between the object and its complement, in that the object and its complement can be paraphrased by a SVC structure, like this:

They elected her (O) Chair of the department (C).

She (S) is Chair of the department (C).

Agreement. Object complements usually agree with the object in number (singular or plural).

She made Liz and Emily (DO) her assistants (OC).

She made Frank (DO) her assistant (OC).

The Subject Complement

The subject complement completes a reference to and/or an implication suggested by the subject of the clause. It shares many of the properties of the object complement, notably form and agreement, as described above under the 'Subject' and 'Object Complement' subheadings. Yet it has a few properties unique to itself, such as position.

Position. The subject complement always occurs after a copular verb in the SVC clause pattern. The most common copular verb in English is the verb be used as a main verb, although other verbs that relate to perception also serve in this category, such as appear, seem, look, sound, feel, etc.

The Adverbial and Adverbial Complement

Another functional constituent that suggests a copular relationship with some other clause constituent is the adverbial complement. It occurs only in explicit copular relationships referring to the subject, as in

Liz (S) is in the park (AC).

or in implicit copular relationships referring to the object, as in

I put the cookies (DO) in the pantry (AC).

The adverbial complement referring to the object can be paraphrased in a SVC clause, as in

The cookies (S) are in the pantry (AC).

Adverbial complements occur only in those two positions. Adverbials on the other hand are not usually as restricted in position or in reference.

To understand more about these last two functions, we should learn to identify adverbials in general by their form, position, and meaning.

Form. The adverbial is normally an adverb phrase, prepositional phrase, or a clause. Occasionally, a noun phrase can function as an adverbial.

Later (A), I will finish the book.

In the afternoon (A), I will finish the book.

When I get home (A), I will finish the book.

Next week (A), I will finish the book.

Position. As we have seen above, the adverbial can occur in many different positions with a clause. The adverbial may be at the beginning (clause-initial), in the middle (clause-medial), or at the end (clause-final). Indeed, even its clause-medial position reveals an enormous degree of "flexibility."

Frankly (A), John was disappointed. [initial]

John, frankly (A), was disappointed. [medial]

John was, frankly (A), disappointed. [medial]

John was disappointed, frankly (A). [Final]

(By contrast, we know that the adverbial complement is restricted in its position to follow either a copular verb or an object.)

Further we should note that not all the adverbials in English are as "mobile" as the example above. Though, generally speaking, adverbials do give the speaker the greatest degree of positional choice of all the clause constituents.

Meaning. The adverbial conveys a definable, but wide-ranging, set of meanings.

Yesterday (A), Ted left. [time]

If possible (A), ring me later. [contingency]

The book fell on the floor (A). [place]

If it rains (A), we'll leave later. [condition]

Although he's young (A), he's good. [concession]

While she slept (A), I worked. [contrast]

I would go, except I can't (A). [exception]

Knowing her (A), I chose a red one. [reason]

To open the lock (A), tug on the door. [purpose]

I fed the stray, to gain its trust (A). [result]

The dog obeyed, as instructed (A). [comparison]

I would fight, rather than quit (A). [preference]

Ankara, I believe (A), is the capital. [comment]

Finally, we should remember one last, but important, difference between the adverbial and all other functional constituents: the adverbial is the optional constituent; it can be left out of the clause; all others are obligatory.

Having completed this brief survey of the clause, we should always remember, one, that there is always much more to be said than this meager outline can cover and, two, that there is always a much greater variety of grammatical structure in the world's language than this chapter could ever hope to show (cf. Curme 1931 and Quirk et al. 1985).

Nonetheless, before we end this discussion, we need to talk about a few more points.

Grammatical Ambiguity

Words, as we know, often have more than one meaning, and that is the classic instance of ambiguity. Ambiguity has another sense, however. Occasionally, phrases and clauses create ambiguity because their structures may be interpreted in more than one way, leading to different meanings for the sentence as a whole. Such ambiguity is called 'grammatical ambiguity.'

(1) An example of grammatical ambiguity at the phrase rank, interpreting her duck as a noun phrase

EXAMPLE	I	saw	her	duck.
FORM	Pronoun	Verb	Determiner [Noun	Noun Phrase]
FUNCTION	Subject	Verb	Object

Compare tables (1) and (2) for an example of grammatical ambiguity.

(2) An example of grammatical ambiguity at the phrase rank, interpreting duck as a subordinate clause

EXAMPLE	I	saw	her	duck.
FORM	Pronoun	Verb	Pronoun	Infinitive Verb
FUNCTION	Subject	Verb	Direct Object	Subordinate Clause

At the clause rank, ambiguity arises when clause constituents can be interpreted as having two or more functions. Consider the clause They found me a good worker, where the functions of the last two constituents can vary, creating two different meanings. Compare tables (3) and (4).

(3) An example of grammatical ambiguity at the clause rank, interpreting me as an indirect object (meaning "They found a good worker for me")

EXAMPLE	They	found	me	a good worker.
FUNCTION	Subject	Verb	Indirect Object	Direct Object

Now compare example (4).

(4) An example of grammatical ambiguity at the clause rank, interpreting me as a direct object (meaning "They feel that I am a good worker")

EXAMPLE	They	found	me	a good worker.
FUNCTION	Subject	Verb	Direct Object	Object Complement

REFERENCES

Curme, George.

1931 A Grammar of the English Language, 2 volumes. New York: D. C. Heath and Company.

Halliday, Michael A. K.

1994 Introduction to Functional Grammar, 2nd ed. London: Edward Arnold.

Quirk, R., S. Greenbaum, G. Leech, and J. Svartvik.

1985 A Comprehensive Grammar of the English Language, London: Longman.