If you want to revise Unfamiliar Texts go to BBC Bitesize. Try the section ‘Appreciating the writer’s craft’. I have added an extract below which discusses why writers do not always follow the ‘rules’.
* Writers deliberately leave out things like subjects and verbs for effect. This sometimes helps to focus ideas on the ‘action’ of a sentence if it is the subject which is omitted: the words around such ‘sentences’ – the context – will have already informed the reader who or what the subject is.
* Writers deliberately repeat expressions for effect (e.g. At first, they were happy. At first, they were completely satisfied. At first, everything was perfect. That was at first).
* Writers deliberately repeat words like conjunctions (‘and’ and ‘but’), to suggest a build-up of ideas, or to indicate the number of things which happen at the one time. This means a sentence becomes unusually long.
* Writers deliberately use a technique known as a rhetorical question, where they ask a question not to find an answer, but to provoke thought in the reader; or because it is way of them indicating to the reader that they themselves might be uncertain of something. This shows that they are trying to work out something themselves.
* Writers deliberately open sentences with conjunctions like ‘but’, to emphasise strongly a change of direction in an argument or indicate a distinct point of opposition in a line of thought.
* Writers deliberately use list forms in sentences, whether it be individual words or expressions or phrases, again to indicate a build-up of information, or to stress a particular line of argument.
* There are other possibilities, but hopefully these will give you food for thought for the moment!