1. COMPLEMENTS
A complement is a word or a group of words that completes the meaning of a verb. Two kinds of complements are:
Subject complements and objects of verbs.
A subject complement is a word or group of words that follows a linking verb and renames or describes the subject.
(A linking verb links the subject with a noun or an adjective that tells more about it.

2. Common linking Verbs Forms of be: am, is, are ,was, were, be, been
Other linking Verbs: appear, become, feel, look,
sound, seem, taste.
Example: Butterflies are fragile.
subject lv Complement

3. Predicate Nouns (nominatives) and Predicate Adjectives
Both nouns and adjectives can serve as subject complements.
A predicate noun follows a linking verb and defines or renames the subject.
Example:
Monarch butterflies are insects.
In this sentence butterflies is the subject are is the linking verb insects is the predicate noun. (the word insect defines the subject butterflies)

4. Predicate noun (nominative) continued
Example: Cocoons become butterfly nurseries.
In this sentence
cocoons is the subject
become is the linking verb
nurseries is the predicate noun and it renames the subject.

5. Predicate adjective
A predicate adjective follows a linking verb and describes a quality of the subject.
Example: Monarchs look beautiful.
Subject lv predicate adj.
Beautiful describes the subject monarch.
So lets practice a little.

6. Practice makes perfect! Identify the underlined word as PA or PN
Migration routes are highways in the sky for birds.
The migration of songbirds is difficult to track.
The birds are too little to carry radio transmitters.
Identification bands can be useful in tracking migration.

7. More practice The bands often become loose, however.
Fortunately, the isotope deuterium hs been helpful.
Deuterium is a form of hydrogen found in rainwater.
Deuterium becomes part of plants, insects, and birds.
Deuterium levels become higher as you go farther south.
Now scientists feel hopeful about tracking migrations.