4. Sentence Structures

Sentences come in four basic structures

An independent clause, also called a main clause, forms a simple sentence. There are other types of sentences, each of which is determined by the number and type of clauses it contains. Each of these sentences must have an independent clause, which is combined with a dependent clause or dependent clauses to create other basic types of sentences. The other different types of sentences are compound sentences, complex sentences, and compound-complex sentences.

The type of sentence is determined by the number and type of clauses it contains. It falls into one of the following:



Simple sentence

A simple sentence conveys a single idea and consists of a single independent clause or a main clause. It may have only a subject and one verb: She sings. A simple sentence can be a short one as this one, or it can be a long one as the subject can be a compound subject and the verb too can be a verb phrase. Additionally, it may contain modifying phrases. But a simple sentence does not include a dependent clause (also called a subordinate clause) or another independent clause.


A small monkey sat next to a big fat monkey.

The doctor and the patient are brothers. (Compound subject in bold)

He sneezes and coughs the whole day. (Compound verb in bold)

Covering with flies, the thing smells strongly of rotten fish. (Modifying phrase in bold)



Compound sentence

A compound sentence contains two or more independent clauses or simple sentences, but no dependent clause. It is possible for a compound sentence to have three, four or more independent clauses. But commonly, it contains only two clauses.


These are the three ways a compound sentence can be formed:

Using coordinating conjunctions: and, but, for, nor, or, so, yet.

Using the semicolon or a conjunctive adverb.

Using the colon.


A conjunctive adverb can be used to connect independent clauses. If the two independent clauses forming a compound sentence are very short, the comma before the coordinating conjunction may be omitted.


I am skinny and you are obese. (Two main clauses joined by a conjunction.)

Mary is jogging, but her husband is sleeping.

The children went for a swim; the parents built sandcastles.

We have to leave before seven; otherwise, we will not arrive in time. (Conjunctive adverb connecting two clauses.)

He gave them a warning: either they behaved or they would be told to leave.

She sang and he listened. (No comma used)



Complex sentence

A complex sentence contains an independent clause or main clause and one or more dependent clauses, which are also called subordinate clauses. The subordinate clause has its own subject and verb, and is joined to the main clause by a subordinating conjunction, which can be as, as if, because, even if, if, unless, etc.


A subordinate clause cannot stand on its own as a sentence. It has to join a main clause to form a sentence.


The following show the subordinate clauses in bold.

I stay away from her as she is a big bully.

As she is a big bully, I stay away from her. (Subordinate clause may come earlier.)

She is eating less and less because she is overweight.

When she saw a rat in the kitchen, she screamed until her children rushed downstairs.



Compound-complex sentence

A compound-complex sentence contains two or more independent clauses and one or more dependent clauses. The compound-complex sentence is a combination of a compound sentence and a complex sentence. Like the compound sentence, it has at least two independent clauses, and it has at least one subordinate clause like the complex sentence. 


The following show main clauses in bold and subordinate clauses underlined.
Since we arrived here this morning, we have been watching vultures circling overhead and as many were perched on top of the cliff.
Jane had to go somewhere and she wanted me to look after her baby as if I had nothing else to do.