Sentences are divided into three classes according to their structure: Simple, Complex, Compound. Understanding these structures is fundamental to mastering English syntax and writing varied, effective sentences.
What is a Simple Sentence?
A Simple sentence is one that contains only one subject and one finite verb, expressed or understood.
- He goes there every day.
- Barking dogs seldom bite.
What is a Complex Sentence?
A Complex sentence is one that contains one Principal clause with one or more subordinate clauses. In the following examples, the clauses in italics are Principal:
- I know when he will come.
- This is the boy who helped me.
- He stayed on until I arrived.
- Since you are ill, you need not go.
- Though he is my friend, I cannot support him here.
What is a Compound Sentence?
A Compound sentence is one that contains two or more independent clauses joined together by co-ordinating conjunctions. The principal co-ordinating conjunctions are: And, or, then, but, else, however, therefore.
- I went there and found him ill.
- I am weak, but I can walk.
Co-ordinate clauses are also joined by a Relative Pronoun or Adverb, used in a Continuative, and not in a Restrictive sense, i.e., when the Relative can be broken up into "and he", "and it", "and this", "and there", "but he", etc.
- He helped me, which (=and this) was very kind of him.
- I went to Calcutta, where (=and there) I stayed for one month.
- I went to the Principal who (=and he) spoke kindly to me.
- At last I found him, which (=and this) relieved me of my anxiety.
What are Contracted Sentences?
Compound sentences often appear in a contracted or shortened form in order to avoid the needless repetition of the same word:
With two or more predicates to the same subject:
- He came and (he) delivered a lecture.
- I was pleased but (I) could not do anything.
With two or more subjects to the same predicate:
- They as well as you are wrong.
- Either he (must go) or his brother must go. He is poor, but he is) honest.
Important Notes on Sentence Structure
(a) When two or more nouns are joined by and, they are not separate subjects to the same verb, but one compound (double or multiple) subject to the plural verb following. Thus, "He and his friend left the place," "The man and his wife were poor" are simple sentences with "He and his friend" and "The man and his wife" as their compound or double subject. — Nesfield, Tipping, E. Smith.
[ But MEU gives, “ You and I would rather see that angel.” as an example of a compound sentence. ]
(b) When the subjects joined by and are inseparable, or when two or more nouns, joined by and, denote a single fact, the sentence is not Compound:
- He and I are great friends.
- He and I agreed.
- Meera and Anjali are walking together.
- Curry and rice is my favourite dish.
- The sum and substance of his story is this.
The first sentence cannot be broken up into 'He is a great friend' and "I am a great friend", because neither of these makes any sense. Similarly, the second and third sentences. In the fourth and fifth sentences, the subjects are the Collective ideas conveyed by 'curry and rice' and 'sum and substance'. 'He and I', 'Meera and Anjali', 'curry and rice', 'sum and substance' are compound subjects, and the sentences are all simple.
(c) When two nouns or phrases are connected by the conjunction "or", and the "or" is not used in an alternative sense, they should be regarded as constituting a single subject:
A tribe or caste is part of a nation. Here caste is used merely as another name for tribe — Nesfield.
How to Distinguish Between Complex and Compound Sentences
Whether a sentence is complex or compound is determined by the number of its principal clauses, and not by the number and matter of its subordinate clauses.
A complex sentence may have two or more subordinate clauses joined by co-ordinating conjunctions.
- The boy who came here yesterday and whom you must have seen is my brother.
- As he is ill and the doctor has advised him rest, he cannot come to welcome you.
Similarly, a Compound sentence may have any number of subordinate clauses dependent on its principal clauses.
- (a) I shall go there when you come, but return as soon as you leave the place.
- (b) As he is ill, he cannot move out, but we expect that he will come round before the ceremony ends.
Therefore, to determine whether a sentence with co-ordinating conjunctions is complex or compound, we shall see if the co-ordinate clauses are independent or subordinate. If independent, the whole sentence is compound, but if subordinate, the sentence is complex.
Some use the term "Mixed sentence"; but in view of the arguments given above, it is not desirable.
Each of the co-ordinate clauses of a double or multiple sentence may have one or more subordinate clauses of its own. Thus, "He came and played", and the examples (a) and (b) above are double sentences.
The following are examples of multiple sentences:
- He came to the town, stayed for a few days and then returned to his village home.
- When he was ill, he consulted the doctor who had examined him before ; but as the latter could not diagonise the disease this time, he went to my brother and sought his help
EXERCISE
State whether the following sentences are Simple, Complex or Compound : Pick out the clauses and show their connection :
- I know that he will come.
- When will you go home to see your brother?
- Seeing this, he burst into tears.
- They did not go there, but remained with me all the time.
- There was a boy in our village who once saved a drowning girl.
- When he will come is known to everybody. I left the place after he had come.
- As I am ill, I cannot go there ; but I shall do the needful from here.
- You must work hard : otherwise you will fail.
- If you go there, you will be rewarded.
- I do not want you to go there without your father's permission.
- When I heard that the boy had fallen from the tree, I at once ran to his house and gave him all the help that I could give.
Key Takeaways
- Sentences are categorized by structure into Simple, Complex, and Compound classes.
- A Simple sentence features one subject and one finite verb.
- A Complex sentence contains one Principal clause paired with one or more subordinate clauses.
- A Compound sentence consists of two or more independent clauses joined by co-ordinating conjunctions.
- Grammarians also identify Double and Multiple sentences based on the count of principal co-ordinate clauses.
Quick Practice
Can you identify the sentence structure of "When he will come is known to everybody"? Write your answers and clause breakdowns in the comments below!
Frequently Asked Questions
What is the difference between a simple and a complex sentence?
A simple sentence contains only one subject and one finite verb. A complex sentence contains one Principal clause along with one or more subordinate clauses.
How do you identify a compound sentence?
A compound sentence contains two or more independent clauses joined together by co-ordinating conjunctions like and, or, then, but, else, however, or therefore.