main clause + linker + dependent clauseMain idea first, dependent idea second. In standard short sentences, no comma before the dependent clause.
Complex Sentence
B1A complex sentence has one main clause and one dependent clause. Use linkers like because, when, if, and although to show the relationship.
What you'll learn
- Build one sentence from a main clause and a dependent clause.
- Choose because, when, if, or although by meaning.
- Add a comma after a dependent clause at the start.
- Leave out the comma when the main clause comes first.
- Fix dependent-clause fragments and complete the sentence.
Structure
linker + dependent clause + , + main clauseWhen the dependent clause comes first, add a comma before the main clause.
Build a sentence
Linker
Ideas
I stayed homebecause it was raining
I stayed home because it was raining.
Use because for a reason.
When to use
Reason
Use a complex sentence when one idea explains another. Maria stayed inside because it was snowing.
Time
Use it to show when something happened. When Lisa called, Tom was driving home.
Condition
Use it when one action depends on another. If Anna finishes early, she will join us.
Contrast
Use it when two ideas pull in different directions. Although Dmitri was tired, he kept working.
Markers
becausewhenifalthough
In contrast
vs compound-sentence
A complex sentence has one main clause and one dependent clause. A compound sentence joins two main clauses of equal status.
Common mistakes
Wrong
Because Anna was tired.
Correct
Anna went to bed early because she was tired.
Because starts a dependent clause here, so it needs a main clause to complete the sentence.
Wrong
When Tom arrived we started dinner.
Correct
When Tom arrived, we started dinner.
A dependent clause at the start is followed by a comma before the main clause.
Wrong
We started dinner, when Tom arrived.
Correct
We started dinner when Tom arrived.
When the main clause comes first, standard short sentences do not use a comma before the dependent clause.
Wrong
I took an umbrella although it was raining.
Correct
I took an umbrella because it was raining.
Because gives a reason. Although gives contrast, so it changes the meaning.
Wrong
I stayed home. Because it was raining.
Correct
I stayed home because it was raining.
The because-clause depends on the main clause, so both parts belong in one sentence.
Common misconceptions
❝ A clause with because, when, if, or although can stand alone as a full sentence. ❞
Not in this pattern. These clauses are dependent, so they need a main clause to complete the thought.
❝ Every complex sentence needs a comma. ❞
Use a comma after a dependent clause at the start. If the main clause comes first, short standard sentences normally do not use one.
Skills in this rule (6)
JOIN_MAIN_AND_DEPENDENTw5Join one complete idea with one dependent clause
Build one sentence with a full main clause and a second clause that depends on it. The dependent clause adds time, reason, condition, or contrast.
CHOOSE_LINKER_BY_MEANINGw5Choose the right linker for time, reason, condition, or contrast
Use because for reason, when for time, if for condition, and although for contrast. Pick the linker that matches the relationship between the two ideas.
PUT_DEPENDENT_FIRST_WITH_COMMAw4Use a comma when the dependent clause comes first
When the sentence starts with a dependent clause, put a comma before the main clause. The comma marks the boundary between the two parts.
NO_COMMA_AFTER_MAIN_FIRSTw3Skip the comma when the main clause comes first
When the main clause comes before the dependent clause, do not add a comma in standard short sentences. The sentence flows straight into the dependent clause.
NO_COMPLETE_SENTENCE_AFTER_BECAUSE_ONLYw5Avoid because-only fragments
A clause starting with because, although, when, or if cannot stand alone as a full sentence here. Add the main clause to complete the idea.
PICK_COMPLEX_SENTENCE_USEw3Use a complex sentence to show a clear relationship between ideas
Choose a complex sentence when you want one idea to support, limit, or frame another idea. This helps show which idea is main and which idea gives extra context.