9.3 Types of subordinate clauses (adverbial, relative, nominal)

Types of Subordinate Clauses

A subordinate clause (also called a dependent clause) has a subject and a verb but can't stand alone as a sentence. It depends on a main clause to make complete sense. These clauses come in three types, each doing a different job: adverbial clauses modify verbs, relative clauses give extra information about nouns, and nominal clauses fill noun roles. Knowing which type you're working with helps you punctuate correctly and build more interesting sentences.

Adverbial Clauses

An adverbial clause modifies a verb, adjective, or another adverb, answering questions like when, where, why, how, or under what condition. It always begins with a subordinating conjunction.

Here are the main kinds, organized by the question they answer:

• Time (when?): After the concert ended, we went for dinner.
• Place (where?): Wherever you go, I will follow.
• Reason (why?): Because it was raining, we canceled the picnic.
• Manner (how?): She sang as if she were on stage.
• Condition (under what circumstances?): If it snows, the schools will close.
• Concession (despite what?): Although he studied all night, he still failed the test.

Common subordinating conjunctions to watch for: after, before, while, because, although, if, unless, since, until, wherever, as if.

Placement and punctuation: An adverbial clause can go at the beginning, middle, or end of a sentence. When it comes before the main clause, set it off with a comma: Before the sun rises, the birds begin to sing. When it comes after the main clause, you usually don't need a comma: The birds begin to sing before the sun rises.

Relative Clauses

A relative clause modifies a noun or pronoun (called the antecedent). It starts with a relative pronoun and gives more detail about the noun it's attached to.

Relative pronouns and when to use them:

• who — refers to people (The woman who won the lottery donated half to charity.)
• which — refers to things (The car, which was red, belonged to my neighbor.)
• that — refers to people or things (The book that I borrowed is overdue.)
• whose — shows possession (The student whose essay was selected will read it aloud.)

Restrictive vs. non-restrictive — this distinction matters for both meaning and punctuation:

Notice that that introduces restrictive clauses, while which typically introduces non-restrictive clauses. This is a useful rule of thumb for everyday writing.

Nominal Clauses

A nominal clause (sometimes called a noun clause) does the job of a noun in a sentence. It provides a complete thought that fills a noun slot: subject, direct object, subject complement, or object of a preposition.

Nominal clauses are introduced by words like that, what, who, whom, which, whose, when, where, why, how, whether, and if.

Here's how they function, with examples:

• Subject of a verb: What she said surprised everyone.
• Direct object of a verb: I wonder whether he will come.
• Object of a preposition: The decision depends on what the committee decides.
• Subject complement: The real question is why they left so early.
• Object complement: They made him what he is today.

A quick test: if you can replace the clause with a single pronoun like something or it and the sentence still makes grammatical sense, you're looking at a nominal clause. For example, What she said surprised everyone → It surprised everyone.

Constructing Complex Sentences

To build a complex sentence, follow these steps:

1. Start with an independent clause that expresses your main idea. (The book is due tomorrow.)
2. Choose the type of subordinate clause that adds the information you need: adverbial for context like time or reason, relative for detail about a noun, nominal for a noun-sized idea.
3. Attach it with the right connecting word — a subordinating conjunction for adverbial clauses, a relative pronoun for relative clauses, or a word like that/what/whether for nominal clauses.

You can layer more than one subordinate clause into a single sentence: The book that I borrowed, which was recommended by my professor, is due tomorrow. Here, that I borrowed is a restrictive relative clause and which was recommended by my professor is a non-restrictive one.

Punctuation recap:

• Non-restrictive relative clauses get commas; restrictive ones don't.
• Adverbial clauses at the start of a sentence get a comma after them; at the end, they usually don't.
• Nominal clauses generally need no extra commas since they're acting as core sentence elements.