what is subjective complement is in the nominative?

Answer 1

I'm not sure what you're asking.

A subject complement can either be a predicate nominative or predicate adjective.

Examples:

Predicate nominative:

Mrs. Orange is the best math teacher.

Predicate adjective:

She is very understanding.

Answer 2

Here is an excellent site that explains that.

http://grammar.about.com/od/mo/g/subcaseterm.htm