Happy is the main lexical predicate here. It takes one argument: an experiencer--John. Tall takes one argument: a theme: Mary. (12) *John is being tall. (13) *Mary is being fond of red roses. (14) ...
Adjectives ending in a consonant follow a different pattern. Invariable adjectives do not change their ending according to the noun they describe. We use adjectives to describe things. In Spanish, ...