Comma Splices & Run-on Sentences: Fixes That Instantly Improve Writing

Learn to spot run-ons and comma splices, then fix them with conjunctions, semicolons, or clean sentence splits.

Here’s the topic in a compact form you can screenshot and revise quickly.

| # | Decision rule | |---:|---| | 1 | A comma cannot join two complete sentences by itself—this is the comma splice. | | 2 | Fix options: add a conjunction, use a semicolon, or split into two sentences. | | 3 | In exam writing, short clear sentences often score higher than long messy ones. | | 4 | Practice by underlining independent clauses, then choosing the clean connector. | | 5 | Use punctuation to show logic, not decoration. |

English grammar feels simple until you have to write clearly under time pressure. The trick is to learn **decision rules** (what to choose and when) rather than memorizing a long list of terms. Good grammar is readable grammar: the reader never has to re-check the subject, the time, or the logic. (See our English B2/C1 chapters for hedging and cautious language, cleft sentences and inversion for emphasis, advanced and mixed conditionals, articles in context, and workplace collocations.) German speakers: focus on articles, prepositions, and continuous aspect. Hindi speakers: focus on subject-verb agreement, article presence, and phrasal verbs. If you’re studying for an exam, your goal is not “perfect grammar,” it’s **predictable grammar**: structures you can use reliably. A shorter sentence with clean grammar scores better than a long sentence full of risky clauses. At B2/C1 the examiners reward controlled complexity—hedging, clear connectors, and consistent tense—more than flashy vocabulary alone.

A comma cannot join two complete sentences by itself—this is the comma splice. The key is to identify the **signal** in a sentence and apply the rule automatically, without overthinking.