Chapter 4: Building Sentences — From Simple to Complex

A well-constructed sentence is the basic unit of clear communication. English sentences come in three main structural types, and knowing how to use all three makes your writing dynamic and sophisticated.

The Three Sentence Types

Type	Structure	Example
Simple	One independent clause	The cat slept.
Compound	Two independent clauses joined by a coordinating conjunction	The cat slept, but the dog barked.
Complex	One independent clause + one or more dependent clauses	Although it was raining, she went for a walk.

A compound-complex sentence combines both: two or more independent clauses and at least one dependent clause.

• She studied hard because she wanted to pass, and she did.

Coordinating Conjunctions (FANBOYS)

Use these to join two independent clauses in a compound sentence. Always place a comma before the conjunction.

Conjunction	Meaning	Example
For	reason/cause	I stayed home, for it was cold.
And	addition	She smiled and waved.
Nor	negative addition	He didn’t call, nor did he write.
But	contrast	I wanted to go, but I was tired.
Or	alternative	We can walk, or we can take a taxi.
Yet	contrast (surprising)	It was late, yet she kept working.
So	result	He was hungry, so he ordered pizza.

Subordinating Conjunctions

These introduce dependent clauses in complex sentences. The dependent clause cannot stand alone.

Category	Conjunctions
Time	when, while, after, before, as soon as, until
Cause	because, since, as
Contrast	although, even though, while, whereas
Condition	if, unless, provided that
Purpose	so that, in order that

Comma rule: If the dependent clause comes first, use a comma. If it comes second, no comma is needed.

• ✅ Although she was tired, she finished the report.
• ✅ She finished the report although she was tired.

Common Mistakes

1. Run-on sentences: Joining two independent clauses with only a comma (comma splice): ❌ I love coffee, I drink it every morning. → ✅ I love coffee, so I drink it every morning.
2. Sentence fragments: A dependent clause alone: ❌ Because it was raining. → ✅ Because it was raining, the game was cancelled.
3. Missing comma with fronted subordinate clause: ❌ Although she was tired she kept going. → ✅ Although she was tired, she kept going.

Key Checklist

• I can identify simple, compound, and complex sentences.
• I can correctly use FANBOYS with a comma to form compound sentences.
• I know when to add a comma with subordinating conjunctions.