A complex sentence contains two ideas. Each idea is expressed in a separate clause. A complex sentence contains an independent clause and a dependent clause.
Carefully review the sample sentences and note that the dependent clauses have been underlined. Dependent clauses cannot stand alone. Also note that the dependent clause can be placed at the beginning or the end of a complex sentence. Logic determines its placement.
Examples of Complex Sentences
Ching will proceed with the project once Research and Development approves the first phase.
Once Research and Development approves the first phase, Ching will proceed with the project.
Whenever Shaila detects a computer security breach, she immediately contacts all relevant departments.
Shaila immediately contacts all relevant departments whenever she detects a security breach.
Unless the error is fixed within 24 hours, we will source the product from your competitor.
We will source the product from your competitor unless the error is fixed within 24 hours.
Whenever we close an important deal, our manager treats the entire team to lunch.
Our manager treats the entire team to lunch whenever we close an important deal.
Punctuation of Complex Sentences
Commas are included only when the complex sentence begins with a dependent clause.
Note the differences:
- Because the product samples did not arrive on time, we had to reschedule the meeting. (comma is necessary)
- We had to reschedule the meeting because the product samples did not arrive on time. (no comma)
Signal Words for Complex Sentences
The table below summarizes some common words that signal adverbial or adjective clauses.
| Words to introduce adverb clauses | Words to introduce adjective clauses | ||
|---|---|---|---|
| after | if | why | what, whatever |
| although | once | whenever | which, whichever |
| as, as if | provided that | whether | who |
| as long as | since | while | when |
| as soon as | so that | wherever | where |
| because | that | why | |
| before | though | that | |
| even if, even though | unless |