11.5 Sentences

Most people recognise a sentence as a unit which begins with a capital letter and ends with a full stop (period), a question mark, or an exclamation mark. Of course, this applies only to written sentences. Sentences have also been defined notionally as units which express a "complete thought", though it is not at all clear what a "complete thought" is.

It is more useful to define a sentence syntactically, as a unit which consists of one or more clauses. According to this definition, the following examples are all sentences:

[1] Paul likes football

[2] You can borrow my pen if you need one

[3] Paul likes football and David likes chess

Sentence [1] is a SIMPLE SENTENCE -- it contains only one clause.

Sentence [2] consists of a matrix clause You can borrow my pen if you need one, and a subordinate clause if you need one. This is called a COMPLEX SENTENCE. A complex sentence is defined as a sentence which contains at least one subordinate clause.

Finally, sentence [3] consists of two clauses which are coordinated with each other. This is a COMPOUND sentence.

By using subordination and coordination, sentences can potentially be infinitely long, but in all cases we can analyse them as one or more clauses.

11.6 The Discourse Functions of Sentences

Sentences may be classified according to their use in discourse. We recognise four main sentence types:

• declarative

• Interrogative

• Imperative

• exclamative

11.6.1 Declarative

Declarative sentences are used to convey information or to make statements:

David plays the piano I hope you can come tomorrow We've forgotten the milk

Declarative sentences are by far the most common type.

11.6.2 Interrogative

Interrogative sentences are used in asking questions:

Is this your book? Did you receive my message? Have you found a new job yet?

The examples above are specifically YES/NO INTERROGATIVES, because they elicit a response which is either yes or no.

ALTERNATIVE INTERROGATIVES offer two or more alternative responses:

Should I telephone you or send an email? Do you want tea, coffee, or espresso?

Yes/no interrogatives and alternative interrogatives are introduced by an auxiliary verb.

WH- INTERROGATIVES, on the other hand, are introduced by a wh- word, and they elicit an open-ended response:

What happened? Where do you work? Who won the Cup Final in 1997?

Questions are sometimes tagged onto the end of a declarative sentence:

David plays the piano, doesn't he? We've forgotten the milk, haven't we? There's a big match tonight, isn't there?

These are known as TAG QUESTIONS. They consist of a main or auxiliary verb followed by a pronoun or existential there

11.6.3 Imperative

Imperative sentences are used in issuing orders or directives:

Leave your coat in the hall Give me your phone number Don't shut the door Stop!

Tag questions are sometimes added to the end of imperatives:

Leave your coat in the hall, will you? Write soon, won't you?

In an imperative sentence, the main verb is in the base form. This is an exception to the general rule that matrix clauses are always finite.