There are four basic sentence structures that every sentence will fall under. These are the (1) simple sentence, (2) the compound sentence, (3) the complex sentence and (4) the compound-complex sentence.
A simple sentence is made up of three parts – a subject (or clause), a verb and an object.
Example: The cat found a mouse.
The “cat” is the subject, “found” is the verb and, finally, “mouse” is the object.
A compound sentence is when you have two or more independent subjects (or clauses) that are usually joined or linked by a conjunction.
Example: Betty likes chocolate cake and Michael likes vanilla.
“Betty” and “Michael” are two independent subjects and they are linked by the conjunction “and”.
A complex sentence is when you link an independent clause with a dependent clause. An independent clause is the part of a sentence that could stand alone as a complete sentence. A dependant clause is the part of the sentence that if used alone, would not be a complete sentence.
Example: Peter left when his father arrived.
Let’s break this sentence down. “Peter left” is an independent clause because if removed from the complete sentence above, it would remain a sentence itself, i.e., “Peter left.” On the other hand, “when his father arrived” is a dependent clause. When removed from the complete sentence above, it cannot stand on its own as an independent, complete sentence. This makes this part of the sentence dependent upon “Peter left”.
A compound-complex sentence is a combination of the compound sentence having two or more independent subjects (or clauses) and the complex sentence where you have at least one independent clause and one dependent clause.
Example: He called the ticket agency and they found the seats which were okay.
“He” and “they” are two independent subjects and they are linked by the conjunction “and”. “He called the ticket agency and they found the seats,” is an independent clause. It can stand alone as a complete sentence. However, “which were okay” is the part of the sentence that cannot stand alone as a complete sentence. It is dependent upon “He called the ticket agency and they found the seats.” We then have all of the elements to make this a compound-complex sentence.