Overview

Consider the following sentences. "I went to the record store. I bought some music. I walked home. I listened to the music." This passage sounds dull. You could improve it by using varied sentence structures and clauses so that buying and listening to new music can sound as exciting as it feels.

All of the sentences in the above example are simple sentences. Simple sentences have one complete subject and one complete verb. Compound sentences contain two or more simple sentences. In a compound sentence, the simple sentences are called main clauses. For example, "I went to the record store, and I bought some music." I went to the record store and I bought some music are both main clauses.

Like main clauses, subordinate clauses have both a subject and a verb. However, subordinate clauses cannot stand alone because they do not express a complete thought. Subordinate clauses must always be combined with a main clause. This combination creates a complex sentence. Here's an example: "After I walked home, I listened to the music." After I walked home is the subordinate clause, and I listened to the music is the main clause.

Sometimes a subordinate clause acts as an adjective, an adverb, or a noun. As an adjective clause, it modifies the noun or pronoun in the main clause. An adjective clause is usually introduced by a relative pronoun, such as that, which, or who. "I bought some new music that was on sale." That was on sale is the subordinate clause that modifies the noun music. Sometimes adjective clauses are necessary to make the meaning of the sentence clear. These types of adjective clauses are called essential clauses. You do not use commas to set off an essential clause from the rest of the sentence. For instance, "The aisle that is near the front of the store contains the new releases." A nonessential clause is an adjective clause that is not necessary to make the meaning of a sentence clear, and it is set off with commas from the rest of the sentence. For example, "The store, which is open until ten, is always crowded."

As an adverb clause, a subordinate clause modifies the verb in the main clause. An adverb clause is introduced by a subordinating conjunction, such as after, as, before, or though. "After I walked home, I listened to the music." After I walked home is a subordinate clause that modifies the verb listened. A noun clause may act as the subject, direct object, object of a preposition, or predicate noun in a sentence. "Whoever likes hip-hop goes to that record store." In this example, the subordinate clause whoever likes hip-hop acts as the subject of the sentence.