3. Complex Sentences

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Complex Sentences

complex sentence is an independent clause joined by one or more dependent clauses.  A dependent clause has a subject and a verb, but it is not a complete idea, therefore, it cannot stand alone. 

Forming a Dependent Clause

If we take a simple sentence and add a subordinator, we have a dependent clause.  For example, if we take the sentence, Thomas Edison invented the light bulb, and add the subordinator after, we now have a dependent clause. After Thomas Edison invented the light bulb. 

At this point, the sentence is a fragment because it is not a complete idea. But if we add an independent clause, such as People did not need to use kerosene lights, then we have a complex sentence that is complete. After Thomas Edison invented the light bulb, people did not need to use kerosene lights.

Notice the use of the comma. When a dependent clause is followed by an independent clause, the comma is used. When an independent clause is followed by a dependent clause, the comma is generally not used.

For example: 

  1. Because students study hard, they need to get enough exercise everyday.
  2. Students need to get enough exercise everyday because they study hard.
  3. When Students are finished taking a test, they often leave the classroom.
  4. Students often leave the classroom when they are finished taking a test.

List of Subordinating Conjunctions

Complex Sentences with Adjective Clauses

Sentences with an adjective clause are also called a complex sentence because they contain an independent clause and a dependent clause.

For example:

  1. The school usually has graduation in the park, where the lake is.
  2. Thomas Edison, who made over one thousand inventions, died at the age of 84 in 1931.
  3. The company that makes computer components is hiring new employees.
  4. People who are kind to others are happier.

Sentence Fragments and Run-ons

Sentence fragments are commonly seen when using dependent clauses. A dependent clause has a subject and verb, but it does not express a complete idea. Therefore, it needs an independent clause. 

If a comma does not separate the dependent clause from the independent clause, the sentence becomes a run-on. Note however, this rule applies only when the dependent clause come first.

  • After the project was finished.

This is a sentence fragment because we don’t know what happened after the project was finished. 

To correct the sentence, we need to add an independent clause. After the project was finished, the researches published their findings.

  • When they gave the blankets and food to the hungry.

This sentence also is a fragment because we don’t know what happen when they gave the blankets and food to the hungry.

To correct the sentence, we need to add an independent clause. When they gave the blankets and food to the hungry, other people joined them in the fight against poverty.

  • Although the sign warned students to finish on time they still finished late.

This sentence is a run-on because it has two subjects and two verbs.

To correct the sentence, we simply need to add a comma after the first clause. Although the sign warned students to finish on time, they still finished late.

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