What are subjects?
Every sentence needs a subject, verb, and complete thought. A subject is a noun that does an action in a sentence. In the statement “My cat complains too often,” my cat is the subject because it is the one that complains. My cat is doing the action.
What are linking verbs?
Some verbs, however, are not actions. These include verbs like am, appear, are, being, been, become, and be, among others. These are called linking verbs because they connect the subject to additional information: “My cat is a cantankerous creature.” Here, the verb “is” connects “My cat” to the adjective “cantankerous,” which means that she is argumentative and bad-tempered.
Complete and Simple Subjects
The single noun that “does a verb” is referred to as the simple subject. The simple subject and all of its modifiers is called the complete subject. In the following sentence, the complete subject is underlined and the simple subject is colored blue: The hunched-over, cantankerous cat looked at me with wide-eyed disdain. We know “cat” is the subject because it is doing the verb. Who looked? The cat looked. “The,” “hunched-over,” and “cantankerous” are part of the complete subject, because they are modifying “cat.”
Subjects and verbs need to agree in number. This means that if a plural subject is used it needs to be matched to a plural verb form, and if a singular subject is used it needs to be matched to a singular verb form. Not all verbs change their form. In fact, of the twelve verb forms in table 1 below, only the six in red boxes change depending on their subject.
Note one correction below for the present simple. It should read, "Cantankerous kittens meow."
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