Simple, Compound & Complex Sentences
A simple sentence has one independent clause. A compound sentence joins two independent clauses with a conjunction. A complex sentence has one independent clause and at least one dependent clause.
Independent vs Dependent Clauses
An independent clause can stand alone (it's a complete sentence). A dependent clause cannot stand alone — it needs the independent clause to complete its meaning.
Relative Clauses
Relative clauses give extra information about a noun. Use who/that for people, which/that for things, where for places, when for times. Defining clauses are essential to meaning; non-defining clauses add extra info (with commas).
🎤 Practice Speaking
Say the complete sentence out loud, filling in the blank.
Exercise 1 of 5
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Complex sentences join an independent clause with one or more dependent clauses, letting you express cause, contrast, time, and condition in a single breath.
Independent and Dependent Clauses
An independent clause can stand alone ('I left'). A dependent clause cannot ('because it was late'). Joined, they form a complex sentence ('I left because it was late'). The dependent clause often starts with a subordinator like because, although, when, if.
Punctuation Patterns
If the dependent clause comes first, use a comma: 'Although it rained, we went.' If it comes second, usually no comma. Getting this right makes long sentences readable and your speech well-organized.
Relative Clauses with Who, Which, That
These add detail about a noun: 'The book that I read was good.' 'Who' for people, 'which' for things, 'that' for either in defining clauses. Relative clauses are how fluent speakers pack more meaning into one sentence — practice saying them aloud.
Common Mistakes to Avoid
The biggest trap is the sentence fragment: a dependent clause ('Because it rained') offered as if it were a full sentence. Learners also skip the comma when the dependent clause leads ('Although it rained we went'), misuse who/which/that, and produce run-ons by never subordinating. A complex sentence needs one independent clause plus at least one dependent one joined by a subordinator. Getting this right makes long thoughts readable instead of breathless.
Try This: A Quick Practice
Take two simple sentences and combine them: 'I left' + 'It was late' becomes 'I left because it was late'. Try 'The boy smiled' + 'He won the game' as 'The boy who won the game smiled'. Practise with because, when, and who. SpeakNow's complex-sentence exercise has you say these aloud, which trains both the punctuation logic and the rhythm of longer sentences.
Frequently Asked Questions
What makes a sentence complex?▼
A complex sentence has one independent clause plus at least one dependent clause joined by a subordinator (because, if, when, who). It expresses richer relationships than two simple sentences.
Do I need a comma before a dependent clause?▼
Only when it starts the sentence ('Because it rained, we stayed'). No comma when it follows the main clause.
When do I use 'who' vs 'which' vs 'that'?▼
'Who' for people, 'which' for things (non-defining), 'that' for people or things in defining clauses. SpeakNow's exercises drill these aloud.