Page 26 - Just Enough English Grammar Illustrated Book

Am, are, is, was, and were are all forms of the most commonly
used linking verb to be.

Subject complements are placed after a linking verb.

Example: Maria was an exchange student.

Subject Linking Subject
Verb Complement

In this example, the name Maria is the subject. The linking
verb was is followed by the phrase an exchange student,
which renames or describes the subject Maria. That makes
the noun exchange student the subject complement.
In your mind, replace the linking verb with an equals sign to
remember that both nouns are of equal value. In the first
example, hamburger = winner, and in the second, Maria =
exchange student. Any form of to be, when it acts as a linking
verb, can be represented by an equals sign.

You will learn more about linking verbs in Chapter 4.

1.11 Possessive Nouns: Showing Relationship
or Ownership

Now you will learn how to change the form of a noun to indicate
a close relationship (often ownership) to another noun.

To show relationship or ownership of a noun,
add an apostrophe, either with or without the letter s.

If the singular form of the noun doesn’t end in s, add an
apostrophe followed by the letter s (’s).

Example with Relationship:
the pool’s diving board
the pool diving board

what is
Singular Noun being related to Possessive Noun
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