Easy ACT Sentence Structure Practice Questions

Concept Explanation

Sentence structure on the ACT refers to the grammatical rules governing how independent and dependent clauses are joined to create clear, logical thoughts. At its core, every sentence must contain at least one independent clause—a group of words with a subject and a verb that expresses a complete thought. The ACT English section frequently tests your ability to identify and correct three primary errors: run-on sentences, comma splices, and sentence fragments. Understanding these basics is a foundational step in your ACT Prep journey.

An independent clause can stand alone, while a dependent clause (or subordinate clause) cannot. For example, in the sentence "Because it rained, the game was canceled," the first part is dependent and the second is independent. To join two independent clauses correctly, you must use one of three methods: a period, a semicolon, or a comma plus a coordinating conjunction (FANBOYS: for, and, nor, but, or, yet, so). Failing to use these properly results in a run-on or a comma splice, which are common pitfalls in ACT Grammar Practice Questions.

Fragments occur when a sentence is missing a subject, a verb, or a complete thought. Often, the ACT will try to trick you by providing a long phrase that looks like a sentence but is actually just a dependent clause or a modifier. Learning to spot these is essential for scoring well on ACT English Practice Questions.

Solved Examples

1. Identify the error: "The sun was setting behind the mountains, the temperature began to drop rapidly."
   1. Analyze the structure: Both "The sun was setting behind the mountains" and "the temperature began to drop rapidly" are independent clauses.
   2. Identify the mistake: Joining two independent clauses with only a comma creates a "comma splice."
   3. Correction: Replace the comma with a semicolon or a period. Corrected: "The sun was setting behind the mountains; the temperature began to drop rapidly."
2. Identify the error: "Walking through the park on a crisp autumn afternoon."
   1. Analyze the structure: This phrase contains a participle ("Walking") but lacks a main subject and a conjugated verb performing an action.
   2. Identify the mistake: This is a sentence fragment because it does not express a complete thought.
   3. Correction: Add a subject and a verb. Corrected: "I was walking through the park on a crisp autumn afternoon."
3. Identify the error: "The cake was delicious and it was gone in minutes."
   1. Analyze the structure: "The cake was delicious" and "it was gone in minutes" are two independent clauses.
   2. Identify the mistake: While there is a conjunction ("and"), there is no comma before it. This is a run-on sentence.
   3. Correction: Add a comma before the conjunction. Corrected: "The cake was delicious, and it was gone in minutes."

Practice Questions

1. The library was quiet, most of the students were studying for their final exams in the basement.

2. Sarah finished her marathon in under four hours. Which was a personal best for her after years of training.

3. The new restaurant opened on Tuesday, it has already received several five-star reviews from local critics.

4. I wanted to go to the beach today, however, the weather forecast predicted heavy thunderstorms all afternoon.

5. Although the movie received poor reviews from critics, but it became a massive box-office success.

6. The team practiced every day for three weeks, they finally won the championship trophy on Saturday night.

7. Because she forgot her umbrella at home. Maria got completely soaked during the walk to her office.

8. Some people prefer coffee in the morning others find that tea provides a more gentle caffeine boost.

9. After the long hike up the mountain, the view from the summit was breathtakingly beautiful.

10. The scientist conducted the experiment three times, each time the results were slightly different than before.

Answers & Explanations

1. Correction: The library was quiet; most of the students... (or use a period). This was a comma splice. Two independent clauses cannot be joined by just a comma. You can find more help with this on our ACT Comma Practice Questions page.
2. Correction: ...four hours, which was a personal best... The second part "Which was a personal best..." is a dependent clause and cannot stand alone as its own sentence. It must be attached to the previous sentence with a comma.
3. Correction: ...Tuesday; it has already... (or "Tuesday, and it has already..."). This was a comma splice. Using a semicolon or a comma + FANBOYS fixes the error.
4. Correction: ...today; however, the weather... The word "however" is a conjunctive adverb, not a coordinating conjunction. When it joins two independent clauses, it requires a semicolon before it and a comma after it.
5. Correction: Although the movie received poor reviews from critics, it became... You cannot use both a subordinating conjunction ("Although") and a coordinating conjunction ("but") to link the same two clauses. It creates a redundant structure.
6. Correction: ...weeks, and they finally won... (or use a semicolon). This was a comma splice. Adding the conjunction "and" makes the sentence grammatically correct.
7. Correction: Because she forgot her umbrella at home, Maria got... The first part is a dependent clause starting with "Because." It should not be followed by a period; it must be connected to the independent clause with a comma.
8. Correction: ...morning; others find... (or "morning, but others find..."). This was a run-on sentence where two independent clauses were placed together with no punctuation at all.
9. Correct as written. This sentence correctly uses a dependent introductory phrase followed by a comma and an independent clause. This is a common structure tested alongside ACT Modifier Practice Questions.
10. Correction: ...three times; each time... This was a comma splice. The phrases on both sides of the comma are independent clauses and require stronger punctuation.

1. Which of the following is a correct way to fix a comma splice?

• AReplacing the comma with a semicolon
• BRemoving the comma entirely
• CAdding a second comma
• DChanging the subject of the second clause

Frequently Asked Questions

What is a comma splice on the ACT?

A comma splice occurs when two complete, independent sentences are joined together using only a comma. To fix it, you must use a period, a semicolon, or a comma combined with a coordinating conjunction like "and" or "but."

How do I identify a sentence fragment?

A sentence fragment is a group of words that lacks a subject, a verb, or a complete thought, often leaving the reader waiting for more information. On the ACT, fragments often appear as long descriptive phrases or dependent clauses that have been punctuated as full sentences.

Can I start a sentence with "Because"?

Yes, you can start a sentence with "Because" as long as the dependent clause it creates is followed by an independent clause. For example, "Because I was tired, I went to bed" is a perfectly structured and complete sentence.

What are the FANBOYS?

FANBOYS is an acronym for the seven coordinating conjunctions: For, And, Nor, But, Or, Yet, and So. These words are used with a comma to join two independent clauses together correctly.

Is a semicolon the same as a period?

In terms of sentence structure, a semicolon and a period function similarly because they both separate two independent clauses. The main difference is that a semicolon suggests a closer relationship between the two thoughts than a period does.