Common Errors Intermediate

Run-on Sentences

Learn what run-on sentences are, how to identify them, and the four ways to fix them. A critical writing error in PTE Essay and IELTS Writing that reduces your Grammar band score.

What is Run-on Sentences?

A run-on sentence occurs when two or more independent clauses are joined without appropriate punctuation or a connecting word. They make writing difficult to read and are a significant grammar error in PTE and IELTS. There are four correct ways to fix a run-on sentence.

Rules & Formation

Run-on type 1 — Fused sentence: two independent clauses with no punctuation between them. "She applied for the visa she was rejected." (WRONG)
Run-on type 2 — Comma splice: two independent clauses joined only with a comma. "She applied for the visa, she was rejected." (WRONG — comma alone is insufficient)
Fix 1: Separate into two sentences with a full stop. "She applied for the visa. She was rejected."
Fix 2: Use a coordinating conjunction (FANBOYS) with a comma. "She applied for the visa, but she was rejected."
Fix 3: Use a semicolon. "She applied for the visa; she was rejected."
Fix 4: Use a subordinating conjunction. "Although she applied for the visa, she was rejected."

Examples

❌ Technology is advancing rapidly education must keep pace. → ✅ Technology is advancing rapidly; therefore, education must keep pace.

❌ The results were positive, further research is still needed. → ✅ The results were positive; however, further research is still needed.

❌ The study took three years it produced valuable insights. → ✅ Although the study took three years, it produced valuable insights.

❌ Governments must act now resources are available. → ✅ Governments must act now, as resources are available.

✅ The policy was introduced in 2015. Since then, outcomes have improved significantly. (two sentences)

🎯 Exam Tip — PTE & IELTS

Run-on sentences and comma splices are consistently penalised in PTE Write Essay and IELTS Writing. The comma splice is the most common type — students incorrectly use "however" with only a comma: "The results were positive, however further research is needed." This is a comma splice. Correct: "The results were positive; however, further research is needed." OR "The results were positive. However, further research is needed." Never use a comma alone before "however", "therefore", "moreover", "consequently".

Frequently Asked Questions

Is a comma splice always an error?

In formal academic writing (IELTS and PTE), comma splices are always treated as errors. In literary and informal contexts, comma splices are sometimes used deliberately for stylistic effect: "He came, he saw, he conquered." (Julius Caesar). But in the formal academic register of IELTS Writing and PTE Essay, always correct them.

What is the most common run-on error in IELTS writing?

The most common error is using a conjunctive adverb (however, therefore, furthermore, consequently, moreover) as if it were a coordinating conjunction, with only a comma: "The policy was expensive, however it achieved its goals." The correct forms are: "The policy was expensive; however, it achieved its goals." OR "The policy was expensive. However, it achieved its goals." Remember: conjunctive adverbs are NOT conjunctions and cannot join independent clauses with only a comma.

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