What is a clause?
There are two types of clauses: independent clauses and dependent clauses.
An independent clause can stand alone as a complete sentence.
Example: The Skidmore student passed all her final exams.
A dependent clause cannot stand alone as a complete sentence because it "depends" on more information to finish the thought.
Example: Since the Skidmore student failed all her final exams.
The above clause is a dependent clause because it is not a complete thought. It has a subject and a verb, but the word "since" indicates that there is some information missing.
When you write sentences, you have some choices as to how to use independent and dependent clauses. Just remember these rules:
- You can combine two independent clauses when you use correct punctuation.
- You can combine a dependent clause and an independent clause.
- You simply can use an independent clause as a full sentence.
- You cannot join two dependent clauses to make a full sentence.
- You cannot let a dependent clause stand alone as a sentence.
Example 1: Combining clauses with a coordinating conjunction
When you combine two independent clauses, you need a connecting word along with the
comma. The connecting words are called coordinating conjunctions:
for, and, nor, but, or, yet, so.
Here are two independent clauses, each a full sentence:
Kate was the best player on the team. She was the smartest girl in her graduating class.
To combine these independent clauses, we use a coordinating conjunction:
Kate was the best player on the team, and she was the smartest girl in her graduating class.
Notice we used the coordinating conjunction "and" along with a comma. Also notice that the comma goes before the coordinating conjunction. (A common mistake is to put the comma after the coordinating conjunction.)
Example 2: Combining clauses with a subordinating conjunction
When you combine a dependent clause and an independent clause, you need a subordinating conjunction. Here are some subordinating conjunctions:
since, because, although, after, as, as though, before, if, once, since, though, unless, until, when, whether, while.
Unlike coordinating conjunctions, which join two independent clauses and are placed after the comma that separates the two clauses, subordinating conjunctions are placed at the beginning of a clause - which means they can appear at the very beginning of the sentence.
Example: When the Skidmore student's parents came to visit, they were appalled at the mess in his dorm room.
Notice that we've used the subordinating conjunction "when" at the beginning of the sentence. If we discarded the subordinating conjunction, we could make this into two independent clauses: The Skidmore student's parents came to visit. They were appalled at the mess in his dorm room.
Here's another example: Because Alex wore his Superman costume to school, everyone laughed at him.
Notice that "Because Alex wore his superman costume to school" is a dependent clause that begins with a subordinating conjunction, and "everyone laughed at him" is an independent clause. "Everyone laughed at him" could be a complete sentence, but "Because Alex wore his Superman costume to school" cannot stand as its own sentence. When a dependent clause is followed by an independent clause, separate them with a comma.
Example 3: Combining clauses with a semicolon
You can join two independent clauses by placing a semicolon between them. Make sure the clauses are closely related in meaning.
The lecturer who spoke on Wednesday inspired controversy; the students asked for a study group to consider his topic further.
In the section on punctuation, you'll find more information about using semicolons.