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Every kind of clause

Can it stand alone? If not, what job does it do? Then how clauses add up to the four sentence types.

A clause has a subject-verb pair. First ask whether it can stand alone: does it land as a finished statement, with no subordinator (because, although, when, if) holding it open? Then it's independent. If a subordinator or a relative pronoun (who, whom, whose, which, that) opens it, it's dependent, and the next question is which job it does. Describes a noun and opens with a relative pronoun? Adjective clause; commas only if the sentence could lose it. Tells when, why, where, how, or under what condition? Adverb clause; a comma after it when it comes first. Sits where a noun would, so you can swap in something or it? Noun clause. Then count clauses to name the sentence: one independent clause is simple; two or more independent clauses is compound; one independent plus a dependent is complex; both at once is compound-complex.

Can it stand alone?

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A clause that has a subject and a verb, expresses a complete thought, and can stand alone as a sentence.

Example

I left early.

Passes both checks, a subject-verb pair and a finished thought, however short it is.

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A clause with a subject and a verb that cannot stand alone as a complete sentence.

Example

because it was raining

Has a subject-verb pair, but the word at its front leaves the thought unfinished.

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A word (like because or although) that turns a clause into a dependent clause.

Example

because the bus was late → The bus was late.

The one word that does all the work; remove it and the clause stands alone again.

The three jobs a dependent clause does

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A dependent clause that describes a noun, usually starting with who, which, or that.

Example

The book that I borrowed was overdue.

Describes a noun, opening with who, whom, whose, which, or that.

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A dependent clause that modifies a verb, adjective, or adverb, telling when, where, why, or how.

Example

When the bell rang, the students rushed outside.

Answers when, why, where, how, or under what condition; a comma after it when it comes first.

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A dependent clause that does the job a single noun would do.

Example

I know that she left early. → I know something.

Fills a noun's slot; swap in something and the sentence still works.

Essential or extra?

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A clause that identifies which specific thing is meant, and so is never set off with commas.

Example

Students who finish early may leave.

Tells you which noun is meant, so it takes no commas.

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A clause that adds extra information without changing which thing is meant, and so is set off with commas.

Example

My car, which is ten years old, still runs great.

Adds a fact about a noun already identified, so commas go around it.

From clauses to sentence types