Sentence, Clause, and Phrases
A phrase is one or more words functioning as a unit in a sentence. Typically, phrases consist of a head and a modifier. The main word in a phrase is called the head and is assumed to be an obligatory element in the phrase.
Words that describe the head word or give us more information about it are called modifiers; modifier are seen as optional elements in a phrase. If they come before the head, they are known as pre-modifiers; if they come after the head, they are called post-modifiers.
A noun phrase usually has a noun or a pronoun as its head word, as is exemplified in the linguist, the linguist over there, the omniscient linguist, or the bright, good-looking linguist.
In all of these examples, the head word is linguist. All have a pre-modifying determiner (the). Some noun phrases also have adjectives (omniscient, bright, good-looking), which function as pre-modifiers. Over there, in contrast, functions as a post-modifier.
A verb phrase usually consists of a main verb, such as kill, kiss or teach (the head word) and possibly or optionally any accompanying auxiliary verb, such as might, could, shall or must (the modifier). The distribution of modifiers and head words in verb phrases is best exemplified in the following: We shall overcome, I may have been wrong, or They should have asked the linguists.
A clause, in contrast to a phrase, usually contains at least a subject and a verb phrase, and very often other clause elements such as object, complement and adverbial or adjunct as well. All of them are present in the following sentence:
All linguists -- considered -- the book on emergent grammar -- a masterpiece -- last year.
1. The subject in sentence-initial position is the main person or thing that the clause is about (All linguists). It performs the ‘action’ that is described, so it usually comes before the verb phrase. The subject is an obligatory unit in English declarative sentences (i.e. declarative sentences make statements)
2. The verb (considered) is the second element and typically expresses actions (kill, kiss), mental states and processes (know, think, consider), acts of communication (speak, say, tell), existence (remain, live, be) or occurrence (happen, change, occur). The verb is an obligatory unit in English declarative sentences.
3. The object (the book on emergent grammar) normally follows the verb and usually provides an answer to the question ‘Who or what has something been done to?’ Objects can be obligatory or optional in English declarative sentences, depending on the verb.
4. The complement (a masterpiece) in this case gives more information about the object (the book on emergent grammar). The complement is an obligatory unit in English declarative sentences, depending on the verb.
5. The adverbial or adjunct (last year) is usually a kind of optional extra in a sentence. It normally provides information on time (last year), on place (in the English Department) or on manner (softly, quietly, surreptitiously). Adverbials or adjuncts can occupy different positions in a sentence.
Interestingly, the units that make up clauses can be combined in eight different ways:
1. subject+verb: She+snores.
2. subject+verb+object: She+killed+the linguist.
3. subject+verb+indirect object+direct object: Mary+sent+Bob+a love letter.
4. subject+verb+direct object+oblique: Mary+sent+a love letter+to Bob. (note: prepositional phrase does not function as an indirect object)
5. subject+verb+complement: Linguists+are+shy.
6. subject+verb+direct object+complement: The linguist+called+the project+rubbish.
7. subject+verb+adverbial: The baby+slept+peacefully.
8. subject+verb+direct object+adverbial: I+prepared+my lecture+last week.