Compound Sentences

A compound sentence is a sentence structure that connects multiple related ideas. It allows you to merge simple thoughts to show relationship, contrast, or cause-and-effect.

1. Grammatical Definition

A compound sentence contains at least two independent clauses joined together. It has no dependent clauses. Each clause in a compound sentence is of equal importance and could stand alone as a separate sentence.

Formula: Independent Clause + Connection + Independent Clause

  • I wanted to walk, but it started to rain.

2. Three Ways to Build a Compound Sentence

There are three ways to join independent clauses in a compound sentence:

A. Using Coordinating Conjunctions (FANBOYS)

This is the most common method. You must use a comma before the conjunction.

  • The FANBOYS Conjunctions: For, And, Nor, But, Or, Yet, So.
  • The sky was dark, so we turned on the lights.
  • She studied hard, yet she failed the exam.

B. Using a Semicolon (;)

You can join two independent clauses with only a semicolon if the ideas are closely related. No conjunction is used.

  • My sister prefers tea; I prefer coffee.
  • The alarm rang; he woke up instantly.

C. Using Conjunctive Adverbs (Transition Words)

You can use transition words (however, therefore, moreover, meanwhile, otherwise) to show logical relationships.

  • Punctuation Rule: Place a semicolon before the conjunctive adverb and a comma after it.
  • I wanted to call you; however, I lost your phone number.
  • The store was closed; therefore, we went home empty-handed.

3. Punctuation Warning: Comma Splices

CAUTION Joining two independent clauses with only a comma (without a coordinating conjunction) is a major grammatical error called a comma splice.

  • Incorrect: I woke up early, I went for a run. (Comma splice).
  • Correct: I woke up early, and I went for a run. (Using and).
  • Correct: I woke up early; I went for a run. (Using a semicolon).

Complete Sentence Examples

Here are more examples of compound sentences:

  1. The coffee was hot, so I drank it slowly.
  2. You can study now, or you can play games later.
  3. The laptop was cheap; however, its performance was terrible.
  4. My father loves fishing; my mother prefers gardening.
  5. We arrived at the station early, and the train was on time.
  6. He did not study, nor did he pass the test. (Note the inversion with nor).
  7. She wanted a cat, yet her roommate was allergic to animals.
  8. The sun had set; meanwhile, the stars began to appear.