Basic linguistic notions

1. The classifying function of the indefinite article is realized in the so-called classifying utterances. Their invariant sentence pattern is: N + Vbe + N1. Those are:
a) structures with the verb “to be”, for example:
This is a computer.
b)exclamatory sentences beginning with “what” or such.
e.g. What a long story! He is such a nuisance!
c) sentences including an adverbial modifier of manner or comparison, for example:
e.g. You look like a rose! She works as a teacher.
2. The indefinitizing function is realized when the referent of the noun is not a real thing, but it exists in the speaker’s imagination only. Those are sentences containing modal verbs or verbs with modal meaning, forms of the Subjunctive Mood, Future Tense forms, negative and interrogative sentences.
e.g. I wish I had a home like you do.
Have you ever seen a living tiger?
3. The introductory function. Before sharing some information about the object, we need to introduce it to the hearer. Fairy tales can be used as ideal illustrations of the use of the indefinite article in its introductory function.
e.g. Once upon a time there lived an old man. He had a wife and a daughter. He lived in a small house.
4. The quantifying function. The indefinite article developed from the numeral “one”. The meaning of “oneness” is still preserved when the article is used with nouns denoting measure, like “a minute”, “a year” or “a pound”.
FUNCTIONS OF THE DEFINITE ARTICLE
The definite article may be used in the following functions:
1. The identifying function
When we speak, we may want to point out to something that both us and the hearer perceive with our organs of feeling. There are five different ways of getting the information about something existing in the objective reality. We can see it (Do you like the picture?), hear it (I believe, the music is too loud), feel it (The pillow is so soft!), smell it (What is the name of the perfume?) or taste it (The soup tastes bitter).