About this lesson
A full sentence needs a subject, a verb and a finished idea. The subject is the person or thing the sentence tells about. The verb tells what happens. If one part is missing, you have a fragment. A fragment is only a piece of a sentence. If two full sentences are pushed together, you have a run-on. When only a comma sits between them, teachers call it a comma splice.
Teachers show four ways to fix the join. You can end the first sentence with a full stop. You can add a comma and a joining word such as and or but. You can use a semicolon (;) when the two ideas are closely linked. Or you can start one half with a word such as because or although. That half then depends on the other.
Teachers add a few small rules. Words like however and therefore cannot join two sentences with just a comma. Put a comma after an opening clause. In a one-sentence PTE summary, an extra full stop breaks the rule. Check for it. Teachers disagree on small points. One example is the comma before the last list item.
Examples from the clips
- English with Emma quizzes you on four sentences, then shows four fixes.
- Sparkle English fixes eight practice sentences one by one. Two are already correct.
- Khan Academy puts a run-on and a comma splice side by side and fixes both.
- E2 PTE warns that words like however can turn a one-sentence summary into two sentences.
Questions this lesson answers
What is a run-on sentence?
It is two full sentences pushed together without a proper break. Some have no mark between them. Some have only a comma, which teachers call a comma splice.
Is a long sentence always a run-on?
No. A long sentence is fine if it is joined correctly. Check the join, not the length.
When can I use a semicolon?
Use it when both sides are full sentences and the ideas are closely linked. Start the next word with a small letter. Do not use it before and or but.
Can I put a comma before however?
A comma alone is not enough. Use a full stop or semicolon first. Then follow however with a comma.
Do exams score punctuation?
Some teachers say it counts inside grammar and form. They show no official proof. Check the official criteria for your own test.