A complex sentence combines one independent clause with at least one dependent clause. A clause is a group of words built around a verb, usually with a subject. An independent clause can stand alone as a sentence. A dependent clause works as part of a larger sentence and can give a reason, describe a noun, or report what someone said.
In Because the rain eased, we opened the courtyard, the independent clause we opened the courtyard tells you what happened. The dependent clause because the rain eased gives the reason. Putting the clauses together makes the connection clear.
Find the independent and dependent clauses
Look for a subject and its verb. In After the caretaker unlocked the gate, the visitors walked in, the caretaker goes with unlocked and the visitors goes with walked. Now read each group on its own.
- The visitors walked in. This clause can stand on its own.
- After the caretaker unlocked the gate … This clause leaves you waiting to hear what happened after the gate opened.
Changing a clause’s position usually leaves its job intact. The visitors walked in after the caretaker unlocked the gate has the same two clauses and gives the arrival first. Purdue OWL on independent and dependent clauses.
Compare simple, compound, and complex sentences
| Type | Example | Clauses |
|---|---|---|
| Simple | We opened the courtyard. | One independent |
| Compound | The rain eased, and we opened the courtyard. | Two independent |
| Complex | Because the rain eased, we opened the courtyard. | One independent, one dependent |
| Compound-complex | Because the rain eased, we opened the courtyard, and the band moved outside. | Two independent, one dependent |
Count clauses to identify the structure. We opened the courtyard and carried out the chairs is simple. One subject, we, performs both actions.
Identify what the dependent clause does
Adverb clauses give the circumstances
These clauses tell you when, why, or under what conditions something happens. In We moved inside because the wind picked up, the clause gives a reason. In If the wind eases, we can go back outside, it sets a condition. Words such as when, because, if, and although often introduce these clauses.
Relative clauses describe a noun
In The chairs that were near the gate got wet, the clause identifies which chairs got wet. In Our front-row chairs, which were near the gate, got wet, the clause adds a detail about chairs the reader can already identify. Relative Clauses in English.
Noun clauses fill a slot a noun can fill
In We heard that the band was ready, the clause tells what we heard. In What the band needs is a dry place to set up, the dependent clause is the subject of the sentence. These clauses are often introduced by that or a question word.
Put punctuation where the clauses meet
Use a comma after an introductory adverb clause. When the main clause comes first, a following adverb clause often needs no comma.
- When the wind eased, the band moved outside.
- The band moved outside when the wind eased.
Use commas around a relative clause that adds a detail. Leave the commas out when the clause identifies which people or things you mean. A noun clause that completes a verb usually follows it without a comma, as in We learned that the gate was open. Comma rules and examples.
Check both sides of a semicolon
A semicolon can join two closely related independent clauses. The band was ready; the rain was still falling. To express a contrast using a dependent clause, write Although the band was ready, the rain was still falling. The introductory clause ends with a comma. Purdue OWL on sentence punctuation.
A worked revision for clearer instructions
Draft. Because the west gate was locked. Visitors who had early tickets waited outside and the volunteers opened the east entrance.
- Find the fragment. The first group starts with because and needs a main clause.
- Match the reason to the action. The locked gate explains why visitors waited. Connect those ideas directly.
- Give the next action room. The volunteers’ action can be its own sentence.
Revision. Because the west gate was locked, visitors who had early tickets waited outside. The volunteers opened the east entrance. The first sentence keeps two dependent clauses, each close to what it explains. Read your revision aloud and ask a reader which gate opened if the location still seems unclear.
Practice spotting and punctuating clauses
- Find the dependent clause in We reopened the trail after the snow melted.
- Add punctuation to Before the workshop began we checked the microphones.
- Identify the sentence type in The rain stopped, and the market reopened.
- Add commas to The east gate which faces the station closes at six. The station detail is extra.
- Find the noun clause in We learned that the bus was delayed.
- Fix the fragment in Although the room was full. We found two seats near the door.
Show answers and explanations
- After the snow melted. It tells when the trail reopened.
- Before the workshop began, we checked the microphones. The introductory clause ends at began.
- Compound. Both clauses can stand on their own.
- The east gate, which faces the station, closes at six. The commas mark an added detail.
- That the bus was delayed. It tells what we learned.
- Although the room was full, we found two seats near the door. The comma connects the introductory clause to its main clause.
