Level: B2-C1

Comma Splices and Run-on Sentences — Practice

A comma splice joins two independent clauses with JUST a comma. A run-on sentence joins them with NOTHING. Both are mistakes. Practice recognizing and fixing them in 29 ESL examples — fix with FANBOYS, a semicolon, or by splitting into two sentences.

📝 Conjunctions unit · lesson 10 of 11 ⏱ about 7 minutes 🔊 every example has audio

Builds on Sentence Types Next in unit Identify Conjunctions →

Comma splices and run-ons — quick guide

When you join two independent clauses, you MUST use one of three correct ways. Using just a comma (or nothing at all) is wrong.

I was tired, I went to bed.

I was tired, so I went to bed.

It started raining we went inside.

It started raining, so we went inside.

🎯 Three ways to fix it

Add a FANBOYS conjunction with a comma:
I was tired, so I went to bed.
Use a semicolon:
I was tired; I went to bed.
Make two separate sentences:
I was tired. I went to bed.

You can also fix it by making one clause dependent (with a subordinator): Because I was tired, I went to bed.

📖 Want the full explanation? See English Conjunctions → Common mistakes on the main grammar page.

Incorrect: Comma splice — TWO independent clauses joined by JUST a comma
I was tired, I went to bed. – Incorrect (Comma splice)
It started raining, we went inside. – Incorrect (Comma splice)
She loves coffee, he prefers tea. – Incorrect (Comma splice)
The cake was sweet, the icing was too rich. – Incorrect (Comma splice)
He worked all day, he felt exhausted. – Incorrect (Comma splice)
I went to the store, I bought some milk. – Incorrect (Comma splice)
The sun set, the stars came out. – Incorrect (Comma splice)
She studied hard, she still failed. – Incorrect (Comma splice)
Incorrect: Run-on — TWO independent clauses joined by NOTHING
It started raining we went inside. – Incorrect (Run-on)
I was tired I went to bed. – Incorrect (Run-on)
She loves coffee he prefers tea. – Incorrect (Run-on)
The cake was sweet the icing was too rich. – Incorrect (Run-on)
The sun set the stars came out. – Incorrect (Run-on)
I went to the store I bought some milk. – Incorrect (Run-on)
He worked all day he felt exhausted. – Incorrect (Run-on)
Correct — fixed with FANBOYS + comma
I was tired, so I went to bed. – Correct
It started raining, so we went inside. – Correct
She loves coffee, but he prefers tea. – Correct
He worked all day, and he felt exhausted. – Correct
The sun set, and the stars came out. – Correct
I went to the store, and I bought some milk. – Correct
Correct — fixed with semicolon
I was tired; I went to bed. – Correct
The sun set; the stars came out. – Correct
She loves coffee; he prefers tea. – Correct
She studied hard; she still failed. – Correct
Correct — fixed by making one clause dependent
Because I was tired, I went to bed. – Correct
When it started raining, we went inside. – Correct
Although she studied hard, she still failed. – Correct
After the sun set, the stars came out. – Correct

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