Run-On Sentences Grammar Quiz
12 multiple-choice questions on run-on sentences: fused sentences, comma splices, and the four standard ways to fix them. B1–B2 level.
This quiz checks how confidently you can apply Run-On Sentences at B1–B2 level, with questions built around real forms such as fused sentence, comma splice, Use a semicolon., Coordinating conjunctions and independent clauses rather than abstract rule statements. Each question presents a full example sentence, so you have to judge which form fits the meaning and structure correctly instead of recalling a rule in isolation.
If a question catches you out, the FAQ section below explains the underlying rule in more detail, including common mistakes learners make with this point. Reviewing the explanation immediately after an incorrect answer, then retrying the quiz on a different day, builds more durable grammar knowledge than repeating the same 12 questions back to back.
Run-On Sentences — FAQ
What is a run-on sentence?
A run-on sentence occurs when two or more independent clauses are joined incorrectly, without proper punctuation or a connecting word. There are two main types: a fused sentence, which has no separator at all, and a comma splice, which uses only a comma to join the clauses.
What is a 'fused sentence'?
A fused sentence joins two independent clauses with no punctuation or connecting word between them at all, as in 'She was tired she went to bed'. This makes the sentence confusing to read because there is no visual signal showing where one idea ends and the next begins.
What is a 'comma splice'?
A comma splice joins two independent clauses using only a comma, which is too weak a punctuation mark to connect two complete sentences on its own, as in 'She was tired, she went to bed'. A comma alone cannot join two independent clauses without an accompanying coordinating conjunction.
What are the four ways to fix a run-on sentence?
The four standard fixes are: using a full stop to create two separate sentences ('She was tired. She went to bed.'); using a semicolon ('She was tired; she went to bed.'); using a comma plus a coordinating conjunction such as 'so' ('She was tired, so she went to bed.'); or using a subordinating conjunction such as 'because' ('Because she was tired, she went to bed.').
What are the FANBOYS coordinating conjunctions?
FANBOYS is a memory aid for the seven coordinating conjunctions: for, and, nor, but, or, yet, so. When one of these conjunctions is used to join two independent clauses, it must be preceded by a comma, as in 'He studied all night, so he passed the exam.'
When IS a comma correct between two clauses?
A comma is correct when it is followed by a coordinating conjunction (one of the FANBOYS), as in 'She was tired, so she went to bed', or when it separates an introductory subordinate clause from the main clause, as in 'Because she was tired, she went to bed.' A comma alone, without a conjunction, is not enough to join two independent clauses.
What is the 'however trap'?
The 'however trap' refers to the mistake of treating 'however' like a coordinating conjunction and joining two clauses with just a comma before it, as in 'The film was long, however it was excellent.' Because 'however' is a conjunctive adverb, not a coordinating conjunction, the two clauses need a period or semicolon before it, as in 'The film was long. However, it was excellent.'
Why is 'I like coffee, it wakes me up' a run-on sentence?
This is a comma splice because two independent clauses, 'I like coffee' and 'it wakes me up', are joined by only a comma. It can be corrected in several ways: 'I like coffee because it wakes me up', 'I like coffee; it wakes me up', or 'I like coffee. It wakes me up.'
Can a subordinating conjunction fix a run-on sentence?
Yes, using a subordinating conjunction such as 'because', 'although' or 'when' turns one of the clauses into a dependent clause, removing the run-on problem entirely, as in 'Because she was tired, she went to bed.' This method also adds a clear logical relationship between the two ideas, such as cause and effect.
Why are run-on sentences considered a serious writing error?
Run-on sentences are considered serious because they can confuse the reader about where one complete thought ends and another begins, making writing difficult to follow. Correcting run-on sentences with the appropriate punctuation or conjunction is an essential skill for clear, professional and academic writing.