5.3 Complex Sentences: Subordination and Dependent Clauses

Complex sentences use subordination to combine ideas, showing how those ideas relate to each other. They pair a dependent clause (one that can't stand alone) with an independent clause (one that can). This structure lets you express cause-and-effect, contrast, timing, and other logical relationships that simple and compound sentences can't capture as precisely.

Types of Dependent Clauses

Defining and Identifying Dependent Clauses

A dependent clause has a subject and a verb, just like an independent clause. The difference is that it doesn't express a complete thought on its own. It needs to attach to an independent clause to make a full sentence.

For example, "because the road was icy" has a subject (road) and a verb (was), but it leaves you hanging. It only becomes complete when paired with an independent clause: "The bus arrived late because the road was icy."

There are three main types of dependent clauses:

• Adverb clauses modify verbs, adjectives, or adverbs in the main clause
• Relative clauses (also called adjective clauses) modify nouns or pronouns
• Noun clauses function as nouns, filling roles like subject or object

Adverb Clauses

Adverb clauses tell you when, where, why, how, or under what condition the action in the main clause happens. They begin with a subordinating conjunction such as because, although, while, if, since, when, after, or unless.

• "Although she studied all night, she still felt unprepared." (contrast)
• "If the temperature drops below freezing, the pipes could burst." (condition)
• "He left early because he had a dentist appointment." (reason)

Placement matters for punctuation. When an adverb clause comes before the independent clause, use a comma after it. When it comes after, you typically don't need a comma.

• Before: "After the game ended, the fans rushed the field."
• After: "The fans rushed the field after the game ended."

Relative Clauses

Relative clauses modify a noun or pronoun in the main clause. They begin with a relative pronoun (who, whom, whose, which, that) or a relative adverb (when, where, why). These clauses provide additional information about the noun they follow.

• "The teacher who assigned the project gave us two weeks."
• "The café where we met is closing down."

Relative clauses can be essential (restrictive) or non-essential (non-restrictive). This distinction affects both meaning and punctuation, and it's covered in more detail in the Relative Clauses section below.

Noun Clauses

Noun clauses do the work of a noun in a sentence. They can serve as subjects, direct objects, or complements. They often begin with words like that, what, whatever, who, whom, how, when, where, or why.

• As subject: "What she said surprised everyone."
• As direct object: "He didn't know that the test was today."
• As complement: "The problem is that we ran out of time."

Noun clauses replace simple nouns with more detailed, specific information. Instead of "Something surprised everyone," you get "What she said surprised everyone" — which tells the reader exactly what that something was.

Subordination

Understanding Subordination in Sentences

Subordination creates a hierarchy between ideas. The independent clause carries the main point, while the dependent clause provides supporting detail. This is different from coordination (compound sentences), where both clauses get equal weight.

Compare these two versions:

By choosing which idea goes in the dependent clause, you control what the reader focuses on.

Elements of Subordination

Subordinating conjunctions are the words that turn an independent clause into a dependent one. Here are the most common ones, grouped by the relationship they express:

• Cause/reason: because, since, as
• Contrast/concession: although, though, even though, while, whereas
• Time: when, while, after, before, until, since, as soon as
• Condition: if, unless, provided that, as long as

The dependent clause relies on the independent clause for its meaning. Without that connection, the dependent clause is a fragment.

Applying Subordination in Writing

To use subordination effectively, put your most important idea in the independent clause and the supporting detail in the dependent clause.

Steps for combining ideas through subordination:

1. Identify two related ideas you want to connect.
2. Decide which idea is the main point and which is the supporting detail.
3. Choose a subordinating conjunction that expresses the correct relationship (cause, contrast, time, condition).
4. Attach the conjunction to the less important idea, making it the dependent clause.
5. Check your punctuation: comma after a leading dependent clause, usually no comma when it follows.

For example, starting with two simple sentences — "The trail was steep. We kept hiking." — you might write "Although the trail was steep, we kept hiking." The contrast relationship is now clear, and the reader knows the main point is that you kept going.

Varying between simple, compound, and complex sentences keeps your writing from feeling monotonous. If every sentence uses subordination, the rhythm gets heavy. Mix it up.

Relative Clauses

Structure and Function of Relative Clauses

Relative clauses attach directly after the noun or pronoun they modify. They add detail, identify, or describe that noun. Getting them right means understanding two things: which relative pronoun to use, and whether the clause is essential or non-essential.

Essential (restrictive) relative clauses provide information the reader needs to identify the noun. Remove the clause, and the sentence's meaning changes or becomes unclear. These do not use commas.

• "Students that submitted late work received a penalty." (Which students? Only the ones who submitted late.)

Non-essential (non-restrictive) relative clauses add extra information that's nice to know but not necessary for identification. These are set off by commas.

• "Ms. Rivera, who teaches biology, is retiring this year." (We already know who Ms. Rivera is; the clause just adds a detail.)

Types of Relative Pronouns

Each relative pronoun has a specific use:

• Who refers to people and acts as the subject of the relative clause. ("The student who answered first got extra credit.")
• Whom refers to people and acts as the object. ("The author whom we studied won a Nobel Prize.")
• Whose shows possession for people or things. ("The family whose house flooded stayed with neighbors.")
• Which refers to things or animals and is used for non-essential clauses. ("The report, which took three weeks, was finally done.")
• That refers to things or animals and is used for essential clauses. ("The book that you recommended was great.")
• When, where, and why function as relative adverbs in clauses about time, place, or reason. ("The year when everything changed was 2020.")

Using Relative Clauses Effectively

• Place the relative clause immediately after the noun it modifies. Misplacement creates confusion. ("She found a ring in the attic that was covered in dust" — was the ring dusty, or the attic?)
• Make sure the relative pronoun agrees with its antecedent (the noun it refers to). Use who/whom for people, which/that for things.
• Relative clauses are great for combining short, choppy sentences. Instead of "The park is downtown. The park has a new fountain," write "The park that is downtown has a new fountain."
• Don't stack multiple relative clauses in one sentence. "The dog that belongs to the neighbor who lives next door that has the red fence..." is hard to follow. Break it up.