If we're learning about commas, why do we have to study subjects?

To use commas properly, you have to be able to identify (and write) a complete sentence.  To do that, you have to identify the subjects of sentences.

What is a subject?

The subject of a sentence is who or what is doing the verb.

Nancy kicked the ball.  (Who kicked?)
The car is blue.  (What is?)

To determine the subject of a sentence, first isolate the verb and then make a question by placing "who?'' or "what?'' before it.  The answer is the subject.

Review this web site from Grammar Bytes. 
When you're finished, click the "back" button to return for a quiz.

Click here when you are ready to take the quiz.