GMAT Sentence Corrections: Sentence structure

Before we can understand sentence structure, we must first understand what a sentence is. We can start by asking, “What makes a sentence a sentence?” 

What are the components of a complete sentence?

Subject – This is the main actor of the thought.

Predicate – This is the verb or action being performed by the subject.

When you combine a subject and a predicate, then you get an independent thought consisting of an actor and distinct action. This is what makes a sentence complete in English. In harder GMAT sentence correction, it can be important to break down your sentences to make sure that they are, in fact, complete,  independent thoughts.

Examples of complete sentences

Port Moresby and its associated suburbs, which were the site of my initial fieldwork, lie within a coastal savanna of low hills, abutting the rugged Owen Stanley mountain range and its forests.

Usually, it is easiest to first identify what the main actor is. In this case, it is “Port Moresby and its associated suburbs“. Which are then described as “lying within the coastal savanna of low hills.” That is your complete sentence; everything else is what is known as the modifier, the descriptive phrase that relates back to the subject and the predicate, in this case, the object of hills to a degree. However, only the two pieces(subject and predicate)make the sentence complete. The other offset clauses separated by commas are just descriptive. So,” which were the site of my initial field work” describes Port Moresby and its associated suburbs. “abutting the rugged Owen Stanley mountain range and its forests” describes the coastal savanna of low hills. All these pieces come together, but the biggest piece is always going to be matching the subject to its predicate. 

What makes a fragment incomplete?

Here are some common GMAT fragment characteristics:

• Unclear subject for the sentence. 
• No main action for any possible subject of the sentence to actively perform. 
• Multiple descriptive clauses refer to different possible subjects, so to a degree, there is ambiguity in where the subject may even lie in the sentence because of how it is structured.

GMAT sentence fragment example

Port Moresby and its associated suburbs are within a coastal savanna of low hills, abutting the rugged Owen Stanley mountain range and its forests, which were the site of my initial fieldwork.

If you were to read this on the GMAT, you’d probably say, “that is long enough to be a sentence.” But what you have to do is interrogate the pieces. So, “Port Moresby and its associated suburbs” is the subject, but there is no verb for this subject because Port Moresby and its associated suburbs are just described as “within the coastal savanna of low hills” and “abutting the rugged Owen Stanley mountain range and its forests” is just describing the coastal savanna of low hills. It is described as “the site of my initial fieldwork.” But, there is no action for any of these possible subjects, making the sentence incomplete and therefore wrong on the GMAT. 

What makes a sentence a run-on?

Here are some common GMAT run-on characteristics:

• Multiple subjects for the sentence. 
• Two main actions for the multiple subjects of the sentence to perform.

GMAT run-on sentence example

My initial fieldwork was in the Savanna; I soon-well, when the rains began- found a specimen of a small Nactus in a patch. 

My initial fieldwork was in the Savanna. With a period, this functions as a complete sentence. Because “My initial field work” is the subject, “was” is the verb, and “in the Savanna” just describes where it was. 

I soon found a specimen of a small Nactus in a patch. This also counts as a sentence on its own because “I” is the subject, “found” is the verb, and “a small Nactus in a patch“ just describes what was found. 

You cannot fuse two complete sentences together with a comma or without any sort of punctuation. There can be some fused sentences involving semicolons or colons, but 99 percent of the time, the GMAT is not testing that issue. You should know that you can use a semicolon to break up a sentence where there are two independent clauses, but it is an issue you will encounter extremely rarely on the GMAT.