The subject of a sentence is the person, place, thing, or idea that is doing or being something. You can find the subject of a sentence if you can find the verb. Ask the question, "Who or what 'verbs' or 'verbed'?" and the answer to that question is the subject. For instance, in the sentence "The computers in the Learning Center must be replaced," the verb is "must be replaced." What must be replaced? The computers. So the subject is "computers." A simple subject is the subject of a sentence stripped of modifiers. The simple subject of the following sentence is issue:

The really important issue of the conference, stripped of all other considerations, is the morality of the nation.

Sometimes, though, a simple subject can be more than one word, even an entire clause. In the following sentence —

What he had already forgotten about computer repair could fill whole volumes,

—the simple subject is not "computer repair," nor is it "what he had forgotten," nor is it "he." Ask what it is that "could fill whole volumes." Your answer should be that the entire underlined clause is the simple subject.

In English, the subject of a command, order, or suggestion — you, the person being directed — is usually left out of the sentence and is said to be the understood subject:

• [You] Step lively there or I'll leave you behind!
• Before assembling the swingset, [you] read these instructions carefully.

For purposes of sentence analysis, the do-er or the initiator of action in a sentence is referred to as the agent of the sentence. In an active sentence, the subject is the agent: