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Run-on sentences: find and fix them
Is every long sentence a run-on?
A run-on sentence joins independent clauses without the necessary punctuation or coordinating conjunction. A fused sentence pushes two complete thoughts together with no punctuation at all. A comma splice inserts only a comma between two independent clauses. In standard edited English, a comma alone is not strong enough to join two complete sentences.
À retenir
- Check whether each part of your sentence can stand alone.
- If both sides are complete statements, separate them with a period, join them with a semicolon, or connect them with a comma and a coordinating conjunction.
- Never rely on a comma alone to separate two independent clauses.
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You need a friend to collect your bike from the repair shop. Your message must make clear that the bike is ready but the shop closes early.
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Comprendre
Comprenez le sens, les situations d’emploi et les erreurs à éviter.
Exemples
The mechanic repaired your gears this morning, but our shop closes early today.
Pourquoi cette forme convient : The comma and but join two complete statements while showing a clear contrast.
3 autres exemples
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The brake cable snapped. Marcus ordered a replacement part online.
The period separates two complete thoughts into independent, easy-to-read sentences.
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The workshop battery was low; the technician attached an external charger.
The semicolon connects two closely related complete statements without an extra conjunction.
-
Because an old chain slipped on hills, Marcus dropped off his bicycle.
The word because makes the first clause dependent, and a comma follows the opening clause.
Lire le guide complet
Find the parts that can stand as sentences
Consider this short message: 'The gears are ready. The repair shop closes at five.' Each part expresses a finished thought that can stand alone as its own sentence. A run-on is not caused by having too many words or too many details; rather, it is a structural problem with how statements are joined. Before you choose any punctuation mark, test each statement independently. Identify who or what the statement concerns, locate the verb, and decide whether the thought is complete, since a subject and verb alone do not guarantee completeness.
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The mechanic adjusted the front brakes.
Pourquoi cette forme convient : This statement has a subject and a verb and expresses a finished thought that stands alone.
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When the mechanic adjusted the front brakes.
Pourquoi cette forme convient : This group has a subject and a verb, but the word when leaves the thought incomplete.
À vous
Why can the statement 'The rear wheel wobbled on hills' stand alone as a sentence?
Réponse : It has a subject and a verb and expresses a complete thought.
Voir la réponse
Réponse : It has a subject and a verb and expresses a complete thought.
The clause contains a clear subject ('The rear wheel'), a verb ('wobbled'), and forms a complete thought without leaving information missing.
Spot missing punctuation and comma splices
When two complete thoughts meet in one sentence, writers often make one of two common errors. A fused sentence pushes two complete statements together with no punctuation between them. A comma splice places only a comma between two complete statements. A comma marks a slight pause, but it cannot hold two independent clauses together in standard writing. Both patterns confuse readers by hiding the sentence boundary.
-
The shop closed at five we arrived too late.
Pourquoi cette forme convient : This is a fused sentence because two complete statements run together with no punctuation.
-
The shop closed at five, we arrived too late.
Pourquoi cette forme convient : This is a comma splice because a comma alone attempts to join two complete statements.
Pour retravailler ce point, essayez Run out of et Optative sentences: choosing hope or wish.
À vous
What error occurs in the sentence 'The chain was loose, Marcus tightened the bolts'?
Réponse : A comma splice joining two complete statements.
Voir la réponse
Réponse : A comma splice joining two complete statements.
Both sides of the comma can stand alone as complete sentences, so joining them with only a comma creates a comma splice.
Separate complete ideas with a period
The most dependable way to repair a run-on sentence is to use a period. Place a period at the end of the first complete statement, and capitalize the first letter of the next word. This choice gives your reader time to absorb the first idea before moving to the next. In everyday workplace messages and quick text updates, two shorter sentences are usually clearer than a crowded compound sentence.
-
The mechanic repaired your gears this morning. The shop closes at six.
Pourquoi cette forme convient : The period creates two distinct sentences, making both facts instantly clear.
-
The tire pressure dropped. We stopped at a service station.
Pourquoi cette forme convient : Each action receives its own sentence, preventing any confusion about timing.
À vous
Which revision correctly fixes the run-on 'The battery died I walked home' using a period?
Réponse : The battery died. I walked home.
Voir la réponse
Réponse : The battery died. I walked home.
A period ends the first complete statement, and the next complete statement begins with a capital letter.
Choose and, but, so, or or to show the connection
You can join two complete statements by placing a comma followed by a coordinating conjunction. Choose your connector by the meaning you want to convey. Use and to add related information, but to present an unexpected contrast, so to indicate a result, and or to offer an alternative. Sequence alone does not justify so; use so only when the second action happens as a direct outcome of the first.
-
The front tire was flat, so Elena walked home.
Pourquoi cette forme convient : The connector so shows that walking home was the direct result of the flat tire.
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The mechanic adjusted the brakes, but the pedal still squeaked.
Pourquoi cette forme convient : The connector but introduces a contrast between the adjustment and the remaining noise.
À vous
Which connector correctly shows that Marcus had two possible choices for his repair?
Réponse : We can replace the chain today, or we can inspect the gears tomorrow.
Voir la réponse
Réponse : We can replace the chain today, or we can inspect the gears tomorrow.
The coordinating conjunction 'or' presents two alternatives for the customer to choose between.
Join closely related complete ideas with a semicolon
A semicolon joins two complete statements that share an immediate, obvious connection. Both sides of the semicolon must be complete sentences that could stand alone. Do not add a coordinating conjunction like and or but directly after the semicolon. In everyday communication, separate sentences with periods are often simpler, but a semicolon remains a polished option when you want to highlight an intimate connection between two thoughts.
-
The workshop closes soon; we must hurry.
Pourquoi cette forme convient : Both sides are complete statements, and their close connection makes a semicolon appropriate.
-
The replacement pedal arrived today; our technician will install it tomorrow.
Pourquoi cette forme convient : The semicolon connects two closely related facts without needing a coordinating word.
À vous
What condition must be met before you can join two parts with a semicolon?
Réponse : Both sides must be complete statements that can stand alone as sentences.
Voir la réponse
Réponse : Both sides must be complete statements that can stand alone as sentences.
A semicolon requires an independent clause on both sides; neither side can be a dependent fragment.
Use because or although to make one part depend on another
You can also repair a run-on sentence by making one clause depend on the other. Words like because and although turn a complete statement into a dependent clause. Because explains a cause, while although introduces a contrast. If you put the dependent clause first, put a comma after it. When the dependent clause follows the main clause, you usually do not need a comma. Never leave a dependent clause standing alone.
-
Because an old chain slipped on hills, Marcus dropped off his bicycle.
Pourquoi cette forme convient : The dependent clause opens the sentence, so a comma separates it from the main clause.
-
Marcus dropped off his bicycle because an old chain slipped on hills.
Pourquoi cette forme convient : When the because clause comes after the main clause, no comma is normally needed.
À vous
Which sentence correctly punctuates an opening dependent clause?
Réponse : Although the workshop was busy, the mechanic inspected my bicycle promptly.
Voir la réponse
Réponse : Although the workshop was busy, the mechanic inspected my bicycle promptly.
An introductory dependent clause starting with 'Although' takes a comma before the main clause.
Give however a complete sentence boundary
A frequent writing mistake is using however like the coordinating conjunction but. Placing a comma on both sides of however between two complete thoughts creates a comma splice. The transition word however is an adverb, not a conjunction. You must establish a complete sentence boundary before it using either a period or a semicolon. Follow however with a comma to signal a pause before the contrasting statement.
-
The bicycle frame was undamaged. However, both wheels needed new spokes.
Pourquoi cette forme convient : A period closes the first sentence, and however begins the next sentence followed by a comma.
-
The bicycle frame was undamaged; however, both wheels needed new spokes.
Pourquoi cette forme convient : A semicolon creates a complete boundary between the clauses, and a comma follows however.
À vous
Which sentence correctly punctuates the transition word however?
Réponse : The repair shop finished early. However, we could not pick up the bike.
Voir la réponse
Réponse : The repair shop finished early. However, we could not pick up the bike.
'However' cannot join two independent clauses with only a comma; it requires a period or semicolon before it.
Keep correct long sentences and shared subjects
Do not assume that every long sentence is a run-on. A sentence can contain multiple clauses and many words if each clause is linked with correct punctuation and conjunctions. In addition, avoid inserting commas unnecessarily before and or but. When one subject carries out two actions joined by a conjunction, you do not place a comma before the conjunction because the second part lacks its own subject.
-
Elena walked into the repair shop and asked for the manager.
Pourquoi cette forme convient : Elena is the subject for both walked and asked, so no comma precedes and.
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Elena walked into the repair shop, and she asked for the manager.
Pourquoi cette forme convient : Because she provides a subject for the second clause, a comma before and is correct.
À vous
Why is there no comma before 'and' in 'The mechanic inspected the frame and oiled the chain'?
Réponse : The sentence has only one subject performing two verbs, not two independent clauses.
Voir la réponse
Réponse : The sentence has only one subject performing two verbs, not two independent clauses.
'The mechanic' is the single subject for both 'inspected' and 'oiled', so no comma is required.
Compare repairs in a punctuation table
Selecting the best repair depends on your context and the relationship you want to emphasize between your complete thoughts. The reference table below compares five standard patterns for repairing run-on sentences. Review each structure to see how punctuation and connecting words define clause boundaries. Use this table as a quick guide when checking your work emails, class assignments, and daily text messages.
| Repair Method | Structural Pattern | Meaning or Use | Example |
|---|---|---|---|
| Period | Complete sentence. Complete sentence. | Separates two distinct statements into independent sentences. | The store closed early. We ordered dinner online. |
| Comma plus connector | Complete idea, and/but/so/or complete idea. | Shows addition, contrast, result, or an alternative choice. | The shop finished the repair, but the battery remained dead. |
| Semicolon | Complete idea; complete idea. | Links two closely related independent thoughts without a connector. | The front tire leaked air; we walked to the bus station. |
| Subordination | Because/Although dependent idea, main idea. | Makes one clause give the reason or contrast for the other. | Because the chain broke, Marcus stopped his ride. |
| Adverbial transition | Complete idea. However, complete idea. | Signals contrast between two distinct sentences. | The frame looked solid. However, the brakes needed oil. |
-
The repair was finished. The shop closed at five.
Pourquoi cette forme convient : A period provides a clear break between two independent facts.
-
The repair was finished, but the shop closed at five.
Pourquoi cette forme convient : A comma plus but highlights the contrast between the completion and the early closing.
À vous
According to the table, which pattern correctly shows an adverbial transition of contrast?
Réponse : Complete idea. However, complete idea.
Voir la réponse
Réponse : Complete idea. However, complete idea.
An adverbial transition like 'However' needs a period or semicolon before it and a comma after it.
Edit a message about collecting a repaired bike
Read this short telephone dialogue about a bike repair: Mechanic: 'Your bicycle is ready, but our workshop closes at five o'clock today.' Marcus: 'My shift ends at six, so I cannot pick it up myself.' Mechanic: 'A colleague can collect it with your ticket, or you can come tomorrow.' When Marcus drafts a follow-up message asking a friend to collect the bike, he must preserve the reason, contrast, and choice from the conversation while avoiding run-on sentences.
-
My bicycle is ready, but the workshop closes at five today. The receipt is on my desk.
Pourquoi cette forme convient : The conjunction 'but' preserves the contrast between the ready bike and early closing time, while a period starts a new sentence.
-
Because the counter closes at five o'clock, could you please collect my bicycle? You can go now, or you can visit before five.
Pourquoi cette forme convient : An introductory 'because' clause preserves the reason, and the second sentence offers an alternative choice using 'or'.
À vous
Which follow-up message correctly preserves the dialogue's contrast and closing time without creating a run-on or comma splice?
Réponse : My bike is ready, but the shop closes at five. You can find the claim ticket on my desk.
Voir la réponse
Réponse : My bike is ready, but the shop closes at five. You can find the claim ticket on my desk.
The first two statements are joined properly with a comma and 'but' to preserve the contrast, and the final statement forms a separate sentence.
Listen for connections without guessing punctuation
Spoken English does not come with visible punctuation marks. When you listen to recorded English or a colleague speaking, speakers naturally pause between thoughts, but a pause alone cannot tell you whether a period, comma, or semicolon is appropriate. To understand the structure of spoken sentences, listen for connecting words like but, so, or because, and identify where one complete message ends and another begins.
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The mechanic replaced your chain this morning, but our store closes at six.
Pourquoi cette forme convient : The audible connector but reveals a contrast between the completed work and the store hours.
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We can fix your squeaky pedals now, or we can inspect your brakes tomorrow.
Pourquoi cette forme convient : The audible connector or indicates that the listener is being offered two options.
À vous
Why is listening for pauses insufficient to determine punctuation in writing?
Réponse : Speakers pause for many natural reasons, including breathing, emphasis, or word choice.
Voir la réponse
Réponse : Speakers pause for many natural reasons, including breathing, emphasis, or word choice.
Pauses reflect speech rhythm and emphasis, so grammatical structure rather than breath determines punctuation.
Find, repair, and explain a run-on from memory
To check your mastery, retrieve the stand-alone test from memory: determine who or what the statement concerns, locate the verb, and confirm that the thought is complete. When you encounter an unpunctuated message, locate where the first independent thought ends and the second begins. Once you identify that clause boundary, choose a repair method that preserves the author's meaning, such as a period or a coordinating conjunction, and explain why your punctuation fits that boundary.
-
The brake cable snapped on Friday. Marcus ordered a replacement wire that evening.
Pourquoi cette forme convient : Separating the clauses with a period establishes a clear boundary between the breakdown and the order.
-
The brake cable snapped on Friday, so Marcus ordered a replacement wire that evening.
Pourquoi cette forme convient : Using a comma and 'so' marks the clause boundary and explains that the order was the direct outcome of the broken cable.
À vous
Read this unpunctuated message: 'The front brake pads arrived early we can install them before lunch.' Which option correctly repairs the clause boundary and explains why the fix works?
Réponse : The front brake pads arrived early, so we can install them before lunch (repaired with a comma and 'so' because the early arrival directly leads to the morning installation).
Voir la réponse
Réponse : The front brake pads arrived early, so we can install them before lunch (repaired with a comma and 'so' because the early arrival directly leads to the morning installation).
The clause boundary sits between 'early' and 'we'. The two complete thoughts are correctly connected using a comma and the coordinating conjunction 'so' because the early arrival directly causes the possibility of morning installation.
Un emploi naturel
Comment utiliser « run-on sentences »
Courant Convient à la plupart des situations, au travail comme entre amis.
Les mots souvent associés
- find run-on sentencesRead your message slowly to find run-on sentences.
- fix run-on sentencesYou can fix run-on sentences by separating complete thoughts with periods.
- avoid run-on sentencesCheck how your complete thoughts connect to avoid run-on sentences.
Vos questions sur « Run-on sentences: find and fix them »
Is every long sentence a run-on?
No. Sentence length does not determine whether a sentence is a run-on. A sentence can contain thirty or forty words and remain completely grammatical as long as all clauses are connected with proper punctuation and joining words. A run-on occurs only when independent clauses are joined improperly, even if the sentence contains only six words.
Although the morning train was delayed by heavy snow and twenty passengers waited on the cold platform, everyone arrived at the conference hall before the opening remarks began.
How can I tell whether both parts are complete sentences?
Read each part in isolation. A complete sentence requires a subject and a verb, and it must express a complete thought that can stand alone. If each part could serve as an independent statement that makes total sense by itself, you have two complete sentences that require a formal boundary or conjunction.
The mechanic finished the inspection.
We picked up the keys.
What is the difference between a run-on and a comma splice?
Run-on sentence is a broad term for any sentence that joins complete thoughts incorrectly. A fused sentence is a run-on with no punctuation between independent clauses. A comma splice is a specific type of run-on where a writer places only a comma between two complete clauses without a coordinating conjunction.
The tire went flat we walked home.
The tire went flat, we walked home.
When should I use a period, a comma, or a semicolon?
Use a period when you want two distinct statements, which is the clearest option in routine writing. Use a comma with a coordinating conjunction like and, but, or so when you want to show addition, contrast, or result. Use a semicolon when two independent clauses are closely linked in thought and you do not want a connector.
The brake cable broke. Marcus ordered a replacement.
The brake cable broke, so Marcus ordered a replacement.
The brake cable broke; Marcus ordered a replacement.
Can I fix a run-on with because or however?
You can fix a run-on with because by turning one complete clause into a dependent clause that explains a cause. In contrast, you cannot fix a run-on simply by adding however with commas. The word however is an adverbial connector and requires a period or semicolon before it, followed by a comma.
Because the shop closed early, Marcus picked up his bike the next day.
The shop closed early; however, Marcus picked up his bike the next day.
Can more than one correction be right?
Yes. Most run-on sentences can be corrected in several valid ways. You might choose two separate sentences with a period, a compound sentence with a comma and a conjunction, or a complex sentence using words like because or although. Your choice depends on which relationship between the ideas you want to highlight.
The rain stopped, so the cyclists continued their ride.
After the rain stopped, the cyclists continued their ride.
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À retenir
Check whether each part of your sentence can stand alone. If both sides are complete statements, separate them with a period, join them with a semicolon, or connect them with a comma and a coordinating conjunction. Never rely on a comma alone to separate two independent clauses.
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