A sentence is a series of words starting with a capital letter and ending with a full-stop.
It might make an assertion:
De Montfort University is in the city of Leicester.
It might ask a question:
Is De Montfort University in Leicester?
It might give a command:
Go to Leicester!
It might request an action:
Would you please contact De Montfort University?
It might express feelings:
I am in two minds about De Montfort University.
HOW LONG SHOULD A SENTENCE BE?
There is no length that a sentence ‘should’ be. A sentence is a long as it’s needed to be.
Sit! That’s a sentence.
‘It is a truth universally acknowledged, that a single man in possession of a good fortune must be in want of a wife.
‘However little known the feelings or views of such a man may be on his first entering a neighbourhood, this truth is so well fixed in the minds of the surrounding families, that he is considered as the rightful property of some one or other of their daughters.’ (Jane Austen.)
Those are also sentences.
The best approach is to write sentences that are neither too long nor too short.
If you write a lot of short sentences, then the effect is rather jerky and childish:-
The man put on his coat. He buttoned it up. He put on his scarf. He pulled on his gloves. He picked up his keys. He opened the door…
It would read better if the sentences were combined:-
The man put on his coat and buttoned it up, put on his scarf and gloves, picked up his keys and opened the door…
However, if sentences are very long, then the reader begins to lose track of the sense:-
The man put on his coat and buttoned it up, put on his scarf and gloves, picked up his keys and opened the door, before remembering that he’d forgotten to check if he’d turned off the gas; and while in the kitchen, he also remembered that he’d meant, the previous day, to write a note for the milkman, cancelling his order for the next fortnight, when he would be holidaying in Florida, and that he might as well call in at the newsagent’s on his way past, and cancel the newspapers as well…
This would be better rewritten in shorter, clearer sentences, as below.
The man put on and buttoned his coat, put on his scarf and gloves, picked up his keys and had opened the door, before he remembered that he’d forgotten to check if he’d turned off the gas. He went into the kitchen to make sure, and while there, recalled that, the previous day, he’d meant to write a note for the milkman. He was going to be holidaying in Florida for the next fortnight, and needed to cancel his milk. And he might as well call in at the newsagent’s on his way past, he thought, as he shut the front door behind him, and cancel the newspapers as well…
The secret to improving sentences is to REWRITE! If a sentence seems unclear or overlong, try writing it another way. (And the italicised paragraph above could do with a few more rewrites.)
Remember, the point of writing is CLARITY. This is especially true of academic writing. Keeping your sentences fairly short helps to make their meaning clear.
Read your work aloud – and listen as you read!
This will help you spot when a sentence is becoming too long and tangled; or when you’ve put awkward sounds together.
CONSTRUCTION OF A SENTENCE.
In English, a sentence has a subject, a verb and an object.
The subject is the thing or person that the sentence is about.
The verb is the word describing the action taken in the sentence.
The object is the person or thing on the receiving end of that action.
SUBJECT VERB OBJECT
He ate his chocolate bar.
He crashed his car.
The building was tall.
She plays rugby.
For a related topic see here