Complete, correct sentences
A complete sentence has a subject, a verb and a complete thought. Two common problems break those rules:
- A fragment is too little: it is missing something.
- A run-on sentence is too much: it crams two or more sentences together without proper punctuation.
Fixing fragments and run-ons makes your writing clear and easy to read. Using different sentence types makes it interesting.
Part 1: Fragments
A fragment looks like a sentence (it starts with a capital and ends with a period) but is incomplete.
Missing a subject
Ran all the way home. Who ran?
Fix: Theo ran all the way home.
Missing a verb
The girl with the purple backpack. What about her?
Fix: The girl with the purple backpack won the spelling bee.
Not a complete thought
Some groups of words have a subject and a verb but still do not finish the thought. They usually begin with words like because, when, if, since, after, although.
Because the bus was late. What happened?
Fix: Because the bus was late, we missed the assembly. Or: We missed the assembly because the bus was late.
Listing fragments
Many animals live in the rainforest. For example, jaguars, sloths and toucans.
Fix: Many animals live in the rainforest, such as jaguars, sloths and toucans.
How to spot a fragment
Ask three questions:
- Who or what is it about? (subject)
- What does the subject do or is? (verb)
- Does it make sense on its own as a complete thought?
If any answer is no, it is a fragment. Reading your work aloud helps, because fragments often sound unfinished.
Part 2: Run-on sentences
A run-on joins two or more independent clauses incorrectly.
Fused sentence (no punctuation)
I love to read I go to the library every week.
Comma splice (only a comma)
I love to read, I go to the library every week.
A comma splice is the most common kind of run-on. A comma alone is not strong enough to join two sentences.
Four ways to fix a run-on
- Make two sentences.
I love to read. I go to the library every week. - Add a comma and a coordinating conjunction (for, and, nor, but, or, yet, so).
I love to read, so I go to the library every week. - Use a semicolon (for closely related ideas).
I love to read; I go to the library every week. - Make one part dependent with a subordinating conjunction.
Because I love to read, I go to the library every week.
“And then” run-ons
Young writers often string ideas together with and: We went to the zoo and we saw lions and then we ate lunch and then we saw monkeys and then we went home.
Fix: break it into sentences and vary the transitions. We went to the zoo and saw the lions. After lunch, we visited the monkeys. Finally, we headed home.
Part 3: The four sentence types
Sentences have different purposes.
| Type | Purpose | End mark | Example |
|---|---|---|---|
| Declarative | makes a statement | period | The library opens at nine. |
| Interrogative | asks a question | question mark | When does the library open? |
| Imperative | gives a command or request | period (or !) | Return your books on time. |
| Exclamatory | shows strong feeling | exclamation mark | What an amazing book that was! |
Notes:
- In a declarative sentence, the subject usually comes first.
- An interrogative sentence often begins with who, what, where, when, why, how, do, is, can.
- In an imperative sentence, the subject you is understood, not written: (You) Close the door.
- An exclamatory sentence expresses strong emotion. Use it sparingly.
Why variety matters
A paragraph of only declarative sentences can feel flat. Mixing in a question can hook a reader; an exclamation can show excitement; an imperative works well in instructions.
Have you ever seen a hummingbird up close? These tiny birds beat their wings up to 80 times per second. Imagine moving that fast! Next time you see one, watch carefully.
Worked examples
Example 1: Fragment or sentence? After the game ended.
Fragment (incomplete thought). Fix: After the game ended, we celebrated.
Example 2: Fix the comma splice. The movie was long, I fell asleep.
The movie was long, so I fell asleep.
Example 3: Name the sentence type. Please pass the salt.
Imperative.
Example 4: Fix the fragment. Such as apples, bananas and grapes.
I like fruits such as apples, bananas and grapes.
Common mistakes
- Thinking long sentences are run-ons. A long sentence can be correct if it is punctuated properly.
- Thinking short groups of words are always fragments. Stop! is a complete imperative sentence.
- Fixing a run-on with just a comma. That creates a comma splice.
- Overusing exclamation marks. Save them for real excitement.
Try it yourself
- Fix the fragment: Hoping to see a whale.
- Fix the run-on in two different ways: It was snowing we built a fort.
- Name the type: Did you finish your project?
- Name the type: What a beautiful sunset!
- Rewrite as an imperative: You should wash your hands before lunch.
Answers: 1. We stood on the deck, hoping to see a whale. 2. It was snowing. We built a fort. / It was snowing, so we built a fort. 3. Interrogative. 4. Exclamatory. 5. Wash your hands before lunch.
Study tip
When proofreading, read your writing backward, one sentence at a time. Without the flow of the story, fragments and run-ons are easier to spot.
Quick recap
- A fragment is missing a subject, a verb or a complete thought.
- A run-on joins sentences incorrectly; a comma splice uses only a comma.
- Fix run-ons with a period, a comma + conjunction, a semicolon or a subordinating conjunction.
- The four sentence types are declarative, interrogative, imperative and exclamatory.
- Vary sentence types to make writing engaging.