Basically, a sentence is a combination of two grammatical units—the subject and the predicate.
Subject
The subject of a sentence refers to what the sentence is about, often the person or thing that carries out the action of the verb. The subject usually gives a clear idea of what the sentence is about.
The subject can be a noun—either a common noun or a proper noun or a verbal noun; a noun phrase; a pronoun; a subordinate clause; an infinitive.
In the following sentences the underlined words form the subject of the sentence and the subjects are nouns:
Dogs need a lot of exercise.
Children play in the park.
Money is extremely important to him.
Marriage is not for him, he says.
Accommodation is expensive in that area.
People are beginning to leave.
Jane is giving a party.
Jim has resigned.
Paris is the capital of France.
Mountaineering can be dangerous.
Dancing is her favourite pastime.
Painting can be a form of relaxation.
In the following sentences the underlined words form the subject of the sentence
and the subjects are noun phrases:
A heatwave has been forecast.
Several unhappy employees have complained to the management.
The large black dog bounded up to the child.
Those terrible floods affected many people.
Representatives from the firm have issued a statement to staff.
James, my brother-in-law and dear friend, has just died.
In the following sentences the underlined words form the subject of the sentence and the subjects are pronouns:
They were found guilty.
We won the battle.
You have passed the exam.
He denied the charge.
She lost her wedding ring.
It has broken down again.
In the following sentences the underlined words form the subject of the sentence and the subjects are subordinate clauses:
Who she was remained a mystery.
Why he left has not yet been revealed.
What he says is not true.
When he will go has not yet been decided.
In the following sentences the underlined words form the subject of the sentence and the subjects are infinitives:
To do that would be unforgivable.
To get there is going to be very difficult.
To marry young is her main aim.
To get through your exams should be your principal concern.
NB: Dummy subject
A dummy subject sometimes has no intrinsic meaning but is inserted to maintain a balanced grammatical structure.
In the sentences:
It has started to rain.
and
It is nearly midnight.
the word It is a dummy subject.
In the sentences
There is nothing else to say.
and
There is no reason for his behaviour.
the word There is a dummy subject.
NB: Directives
In sentences which are directives the subject often does not appear, but is implied, as in: Get this out of here.
and
Lend me that pen for a minute, please.
The implied subject is you.
Predicate
The predicate refers to the part of a sentence or clause that gives information about the subject. It is basically all the parts of a clause or sentence that are not contained in the subject. It can either be a single verb or a number of elements.
Thus in the sentence
The little girl fell.
the word fell is the predicate of the sentence.
Similarly, in the sentence
The tired old man slept soundly.
the words slept soundly form the predicate of the sentence.
And in the sentence
The tired old man slept like a log.
The words slept like a log form the predicate of the sentence.
In the following sentences the underlined words form the predicate of the sentence:
Jane fainted.
Peter was rich and powerful.
Children screamed loudly.
The lights went out all of a sudden.
Workers protested long and loudly at the factory gates.
They are leaving at the end of next week.
We took the stray kittens home.
The students celebrated their exam results all night long.
The child threw the red ball to the dog in the park.