informal words appear in dialogues in which they realistically reflect the speech of modern people:
"You're at some sort of technical college?" she said to Leo, not looking at him ... .
"Yes. I hate it though. I'm not good enough at maths. There's a chap there just down from Cambridge who puts us through it. I can't keep up. Were you good at maths?"
"Not bad. But I imagine school maths are different."
"Well, yes, they are. I can't cope with this stuff at all, it's the whole way of thinking that's beyond me... I think I'm going to chuck it and take a job."
(From The Time of the Angels by I. Murdoch)
However, in modern fiction informal words are not restricted to conversation in their use, but frequently appear in descriptive passages as well. In this way the narrative is endowed with conversational features. The author creates an intimate, warm, informal atmosphere, meeting his reader, as it were, on the level of a friendly talk, especially when the narrative verges upon non-personal direct speech.
"Fred Hardy was a bad lot. Pretty women, chemin de fer, and an unlucky knack for backing the wrong horse had landed him in the bankruptcy court by the time he was twenty-five ...
...If he thought of his past it was with complacency; he had had a good time, he had enjoyed his ups and downs; and now, with good health and a clear conscience, he was prepared to settle down as a country gentleman, damn it, bring up the kids as kids should be brought up; and when the old buffer who sat for his Constituency pegged out, by George, go into Parliament himself."
(From Rain and Other Short Stories by W. S. Maugham)