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Whether you're writing a research paper, crafting a personal essay, or sending a professional email, spotting key sentence parts and understanding how different types of sentences work helps you communicate with clarity and style. 

Basic Sentence Parts

Subject
Who or what does the action?

A subject is a person, animal, place, thing, or concept that does an action. Determine the subject in a sentence by asking the question, “Who or what?”

Example

I like spaghetti.

I = subject

Example

He reads many books.

He = subject

Verb
What is the action or state of being?

A verb expresses what the person, animal, place, thing, or concept does. Determine the verb in a sentence by asking the question, “What was the action or what happened?”

Example

I like spaghetti.

like = verb

Example

He reads many books.

reads = verb

Example: "Be" Verb

The movie is good.

  • The be verb is also sometimes referred to as a “copula” (or a “linking verb”). It links the subject, in this case “the movie,” to the complement or the predicate of the sentence, in this case, “good.”

Object
Who or what receives the action?

A person, animal, place, thing, or concept that receives the action. Determine the object in a sentence by asking the question, “The subject did what?” or “To whom?/For whom?”

Example

I like spaghetti.

spaghetti = object

Example

He reads many books.

many books = object

Dependent Clause
Cannot stand alone. Must attach to an independent clause.

A dependent clause is not a complete sentence. It must be attached to an independent clause to become complete. This is also known as a “subordinate clause.”

Example

Although I like spaghetti

This dependent clause introduces a contrast. It suggests that despite liking spaghetti, something else is true, but we don’t have the rest of the information to know what that is.

Example

Because he reads many books

This dependent clause introduces a reason or cause. It suggests that reading many books leads to some result or consequence, but we don’t know what without additional information.

Independent Clause
Contains a subject and verb, forming a complete idea.

An independent clause can stand alone as a sentence. It contains a subject and a verb and is a complete idea.

Example

I like spaghetti.

  • I = subject
  • like = verb
  • spaghetti = object

Example

Because he reads many books

  • He = subject
  • reads = verb
  • many books = object

Prepositional Phrase
Begins with a preposition (like “in” or “at”) and tells where, when, or in what way.

A phrase that begins with a preposition (like “in,” “at,” “for,” “behind,” “after,” “during”) and modifies a word in the sentence. A prepositional phrase answers one of many questions. Here are a few examples: “Where? When? In what way?”

Example

I like spaghetti for dinner.

This prepositional phrase starts with “for” and provides information about when the spaghetti is preferred.

Example

He reads many books in the library.

This prepositional phrase starts with “in” and provides information about where the reading happens.

Types of Sentences

A simple sentence contains a subject and a verb, and it may also have an object and modifiers. However, it contains only one independent clause. 

Example

She completed her literature review. 

  • She = subject
  • completed = verb
  • her literature review = object

Example

He organized his sources by theme. 

  • He = subject
  • organized = verb
  • his sources = object
  • by theme = prepositional phrase

Example

They studied APA rules for many hours. 

  • They = subject
  • studied = verb
  • APA rules = object
  • for many hours = prepositional phrase

A compound sentence contains at least two independent clauses. These two independent clauses can be combined with a comma and a coordinating conjunction or with a semicolon.

Example

She completed her literature review, and she created her reference list.

  • This sentence has two independent clauses that could each stand alone:
    • Independent Clause #1: “She completed her literature review”
    • Independent Clause #2: “She created her reference list”
  • A comma (,) and coordinating conjunction (“and”) are used to connect these independent clauses.

Example

They studied APA rules for many hours, but they realized there was still much to learn.

  • This sentence has two independent clauses that could each stand alone:
    • Independent Clause #1: “They studied APA rules for many hours”
    • Independent Clause #2: “They realized there was still much to learn”
  • A comma (,) and coordinating conjunction (“but”) are used to connect these independent clauses.

A complex sentence contains at least one independent clause and at least one dependent clause. Dependent clauses can refer to the subject (who, which), the sequence/time (since, while), or the causal elements (because, if) of the independent clause.

In complex sentences, comma placement depends on clause order.

  • If the dependent clause comes first, add a comma after it.
  • If the independent clause comes first, no comma is needed.

Example

Because he organized his sources by theme, it was easier for his readers to follow.

  • Dependent Clause = “Because he organized his sources by theme”
  • Independent Clause = “It was easier for his readers to follow”
  • Note: This sentence begins with the dependent clause. Therefore, a comma is needed after this clause to form the complex sentence.

Example

They studied APA rules for many hours as they were so interesting.

  • This sentence has two independent clauses that could each stand alone:
    • Independent Clause = “They studied APA rules for many hours”
    • Dependent Clause = “as they were so interesting”
    • A comma (,) and coordinating conjunction (“but”) are used to connect these independent clauses.
  • Note:This sentence begins with the independent clause. Therefore, a comma is not needed.

Sentence types can also be combined. A compound-complex sentence contains at least two independent clauses and at least one dependent clause.


Example

She completed her literature review, but she still needs to work on her methods section even though she finished her methods course last semester.

This sentence combines both compound and complex structures.

Compound

  • Two independent clauses that could stand alone: “She completed her literature review” and “She still needs to work on her methods section”
  • These independent clauses are joined by “but” and a comma.

Complex

  • There are two independent clauses.
  • There is a dependent clause (“even though she finished her methods course last semester”) that adds more background information.

Common Sentence Challenges

Overly Broad Sentences

Writing broad, sweeping sentences can weaken your writing and fail to engage readers.

Overly Broad Example

I used a variety of counseling tools on many occasions.

This sentence is too general and does not share much information. What are these tools? How were they used, and when precisely?

Possible revision to narrow the focus: As a counselor, I used active listening, open-ended questions, and eye contact in my initial interviews with clients.

Unnecessary Sentences

Sometimes it can be hard to determine what kind of knowledge a reader brings to your material. You should trust that a reader will understand common concepts in everyday adult life.

Unnecessary Sentence Example

An employee is defined as “a person who works for another person or for a company for wages or a salary” (“Employee,” 2015, para. 1).

Chances are, an educated reader will already know what an employee is, so this definition is not needed.

Sentences Beginning with Coordinating Conjunctions

Although starting sentences with coordinating conjunctions (like “and,” “but,” or “so”) is common in informal writing, formal academic writing typically avoids this practice.

Coordinating Conjunctions Example

I gave my daughter a strawberry. But she said didn’t like it even though she loved them yesterday. So I gave her a peach slice instead. And then she asked for a strawberry.

Revision using a compound sentence: I gave my daughter a strawberry, but she said didn’t like it even though she loved them yesterday, so I gave her a peach slice instead. Then, she asked for a strawberry.

I cleaned our front windows in preparation for the party. But then my toddler woke up from her nap. Needless to say, I cleaned them again. 

Revision using an alternative connecting word: I cleaned our front windows in preparation for the party. However, my toddler woke up from her nap. Needless to say, I cleaned them again.

Run-On Sentences and Sentence Fragments

Sentence fragments lack key components of a complete thought, and run-on sentences incorrectly combine multiple complete thoughts.

Run-On and Fragments Example

Running through the park on Tuesday morning.

This is a sentence fragment. Who was running?

  • Revision: Joyce was running through the park on Tuesday morning.

The experiment failed we had to start over.

This is a run-on sentence. Two independent clauses are incorrectly joined.

  • Revision: The experiment failed, so we had to start over.
 

Learn More about Run-On Sentences and Sentence Fragments

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