Transitive predicates are not the only ones which can have noun phrases as the complement of their verbs. The verb be is a very basic and very hard-working verb in English. As a main verb, be must be followed by a complement following it, and that complement can be a noun phrase, as in the sentences below, but the complement can't be considered an object of the verb, which represents no real action at all. Instead, the complement refers to the subject. Be is also a bit eccentric in form, with a variety of forms matched by no other verb, which is one of the reasons we've done our best to avoid it up until now.

(1) I am a dork.

(2) You are a dork.

(3) He is a dork.

(4) She is a dorkette.

(5) It is a dork-burger.

(6) We are dorks.

(7) They are dorks.

(8) I/she/he/it was a dork.

(9) You/we/they were dorks.

The complements in these sentences (a dork and its variants) all refer back to the subject. A fairly common term for such complements is subject complement. A verb (like be that takes a subject complement is called a linking verb. There are different kinds of subject complements. When it is an noun phrase, like the complements in this section, traditional grammar calls it a predicate nominative. We'll look at other kinds of subject complements in the next section.

Agreement Problems with Predicate Nominatives. Writers sometimes get confused about subject-verb agreement when the subject and a predicate nominative differ in number. Don't worry about the predicate; the subject is what counts:

(10) His problem is his grades.

(11) His grades are his problem.

There is a minor exception to this rule. When the subject is a measure of time, space, or volume, subjects that are plural in form are often taken as a single unit in practice and use singular forms of be or other linking verbs:

(12) Ten yards is a long way.

(13) Two days seems a long time.

Deleting Forms of Be. A less frequent but more serious problem is the omission of the main verb be. The verb in a sentence like "My professor is a dork" adds no real information, and some languages do very well without it. There are also non-standard dialects in which be a main verb is optional--"RHC the man!" Even Standard English speakers will sometimes omit it in particular situations--text messaging, for example. Omitting the be rarely makes the resulting sentence less clear, but it is so serious a departure from the norm of Standard English speakers that a real stigma is attached to its use in writing and even in speech, so it should be avoided in formal situations.

The Different Meanings of Be as a Linking Verb. The complements of linking verbs normally identify an attribute of the subject, or a class to which it belongs. But we also use be to assert that the subject and subject complement are identical--i.e., refer to the same entity. This use of be is mainly found with noun phrase subject complements, often (but not always) beginning with the:

(14) My professor is the biggest dork on campus.

(15) My cousin is Mayor of Melonville.

(16) The biggest dork on campus is my professor.

(17) The Mayor of Melonville is my cousin.

Linking Verbs and Predicate Nominatives. Not all linking verbs can have a noun phrase as their subject complement--be is more versatile than most. Two others that allow predicate nominatives are become and remain. (19):

(18) Janet becomes a woman.

(19) George remains an idiot.

(20) (a) George seems a dork.
(b) George seems to be a dork.
(21) (a) George appears a simple newspaper boy.
	(b) George appears to be a simple newspaper boy.

Dorky Trees. As long as we confine our subject complements to noun phrases, we don't have to change our PS trees at all to accomodate them. For a change, then, let's try building a tree from the ground up:

When we look at My professor is a dork, we see right away that "professor" and "dork" are nouns, and that "is" is a verb. "My" is a possessive personal pronoun, and "the" is a definite article. Both of these seem to be alone in the determiner slot, so we give them both a Det label. Looking at these again, we can see that "my professor" and "a dork" are pairs that belong together. Since they have a determiner as their specifier, these are obviously noun phrases:

The subject of the sentence is "My professor", so the "is" belongs with "a dork" in the verb phrase (VP. At this point we might as well put in the tense element (I) which takes the VP as its complement, marking it -Pst to show that it is in the present tense:

This pretty much labels our sentence (IP). We'll add an I-bar (I') level to show that the sentence can be divided between the specifying subject NP and the rest of the phrase:

Questions with Linking Verbs. As noted earlier, be breaks the rules for main verbs by taking part in INVERSION to make yes/no questions. This works with all kinds of subject complements:

(22)	(a) He is funny.
	(b) Is he funny?
(23)	(a) He is a funny man.
	(b) Is he a funny man?
(24)	(a) He is here.
	(b) Is he here?

(25) He is not funny.

(26) He is funny, isn't he?

Other linking verbs do not have this option, even those which otherwise most closely resemble be in their behavior, even become. The following are not grammatical sentences:

(27) *Seems he a funny man?

(28) *Becomes he a funny man?

Just for the Record--More Terms: A subject complement can also be called a subjective complement or, since it is in the predicate, a subject predicative or predicative complement. The verb be can be called copular or the copula when used as the main verb, and omitting it is sometimes called copula deletion

How Much of This Will be on the Test? Terms to Have in Mind (or look up in the Glossary) The key terms in this section are linking verb, subject complement, and predicate nominative. You probably should know the term copula, and you should be aware that alternative terms for subject complement (subject predicative, predicative complement) exist.