Exercises: Identifying Fragments and Run-on Sentences (Writing Errors)


Fragments and run-on sentences (especially comma splices) are common errors in academic English. To review these grammar points, see our pages on fragments, run-on sentences, and sentence types.

Once you understand independent clauses, dependent clauses, fragments, and run-on sentences, try the exercises below.

Two pencils resting on paper

Exercise Group #1: Complete Sentence or Fragment?

Decide if the below sentences are complete (i.e. complete thoughts) or fragments.

1. On Tuesday morning last week at 8:30 a.m. 

Answers & Explanation

Fragment — ‘On…’ begins a prepositional phrase because ‘on’ is a preposition. This phrase needs to end with a comma, and then a subject and verb should be added. E.g. “On Tuesday morning last week at 8:30 a.m, I drank some milk.”

2. I ate breakfast with my sister. 

Answers & Explanation

Complete Sentence — This sentence has everything it needs. It has a subject (I), a verb (ate), and an object (breakfast).

3. Even though you have lived in another country. 

Answers & Explanation

Fragment — This sentence is a dependent (subordinate) clause. The phrase Even though is a subordinate conjunction. To fix this fragment, you need to add an independent clause. E.g. “Even though you have lived in another country, there are still many things you haven’t learned.”

4. Which is important for success in college. 

Answers & Explanation

Fragment — This is a dependent (subordinate) clause. The sentence is missing a main (independent) clause. E.g. This webpage will help you avoid errors, which is important for success in college.

5. This is important for success in college. 

Answers & Explanation

Complete Sentence — This is a simple sentence. It has everything a sentence needs — a subject (the pronoun This), a verb (is), and a complement (important for success in college).

6. Finding someone to design your company’s website is easy. 

Answers & Explanation

Complete sentence — This is a simple sentence. “Finding someone to design your company’s website” is the subject of the sentence.

7. The way that people learn new skills in this modern world. 

Answers & Explanation

Fragment — The sentence has a subject (“The way that people learn new skills in this modern world“), but it is missing a verb.

Exercise Group #2: Complete Sentence, Fragment, or Run-On? (Intermediate)

Decide if the below sentences are fragments, run-ons, or complete.

1. I ate breakfast my sister did too.

Answers & Explanation

Run-On — There are two sentences here. “I ate breakfast.” and “My sister did too.” To connect these independent clauses, you need a conjunction like “and”.

2. Getting up early in the morning before everyone else does.

Answers & Explanation

Fragment — This is a long subject. You need to add a verb after the subject and then finish the sentence. E.g. Getting up early in the morning before everyone else does isn’t fun.

3. People who live in glass houses shouldn’t throw stones.

Answers & Explanation

Complete sentence — This is a complex sentence. The phrase “who live in glass houses” is an adjective clause and subordinate clause. The main (independent) clause is “People shouldn’t throw stones.

4. If you are happy and you know it and you really want to show it.

Answers & Explanation

Fragment — This is a subordinate clause (“If …..”). The sentence needs a comma, and then a main (independent) clause. E.g. “If you are happy and you know it, clap your hands.”

5. By the time she was 20 years old.

Answers & Explanation

Fragment — This is a dependent/subordinate clause. You need to add an independent/main clause, such as “By the time she was 20 years old, she had lived in five countries.

6. People can do whatever they want it’s up to them.

Answers & Explanation

Run-on — This should be two sentences. “People can do whatever they want. It’s up to them.

 

Exercises Group #3: Complete Sentence, Fragment, or Run-On? (Advanced)

1. Take the pizza out of the oven then let it cool.

Answers & Explanation

Run-on — This should be two sentences. The word ‘then’ is an adverb; it cannot join two independent clauses.

2. The main reason why the leader of this country needs to be replaced immediately is obvious.

Answers & Explanation

Complete sentence — This sentence has a long subject (“The main reason…..immediately“) but the subject is followed by a verb (is). This makes it complete.

3. The student had tried to cheat on the test. Although, he was not successful. (focus on the underlined sentence)

Answers & Explanation

Fragment — The word ‘although’ begins a subordinate/dependent clause. Anytime you want to use ‘although’ (or other subordinate conjunctions), you need to have a subordinate clause and an independent clause in the sentence. If you want to only use one clause, you can use ‘However, he was not successful‘ because the word ‘however’ is not a conjunction (it is an adverb).

4. Placed in a care home for the elderly where visitors could come on the weekend or on a weekday by appointment.

Answers & Explanation

Fragment — This is a fragment. The sentence is incomplete. It is either missing a subject (“People were placed…”) or a main clause that comes afterward.

 

Exercises Group #4: Focus on Punctuation (Advanced)

Test your knowledge of commas, semi-colons, colons, and periods with these exercises.

1. The company didn’t make money, therefore, it went out of business. 

Answers & Explanation

Run-on (Comma splice) — The word ‘therefore’ is not a conjunction. This means it cannot join two clauses.

2. The company didn’t make money, so it went out of business. 

Answers & Explanation

Complete sentence — Here we have two independent clauses joined by a coordinating conjunction (FANBOYS). This is a compound sentence.

3. Please bring the following to the event: water, some comfortable shoes, and ten dollars.

Answers & Explanation

Complete sentence — This is a complete sentence. The colon at the end of the independent clause (‘Please bring the following to the event‘) is used to introduce a list. This is a correct way to use a colon.

5. The man said something quite interesting to me: The longer you live, the less you care about yourself. 

Answers & Explanation

Complete sentence — After an independent clause or complete sentence, a colon can be used to introduce another sentence.

6. The volunteers were divided into two groups, the first group received the medicine and the second group did not. 

Answers & Explanation

Run-on (Comma splice) You cannot put a comma between two independent clauses. You either need to use a period after the first independent clause, or join the two independent clauses with a conjunction.

7. I like to sing in the shower; it’s my favorite part of the day. 

Answers & Explanation

Complete Sentence — A semi-colon functions like a period. Here we have two independent clauses joined by a semi-colon, which is correct.

8. Whenever you need help, just give me a call, I’ll be there for you. 

Answers & Explanation

Run-on (Comma splice) — There are three clauses here. The first clause is a subordinate clause, and the last two are independent clauses. The last two independent clauses cannot be joined by a comma. A conjunction is needed or a period.

If you had problems with the punctuation exercises, please see these pages on colons, semi-colons, and comma-splices.


I hope you have found these exercises useful. If you find a mistake or have a question, please leave a comment below.

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