Some Grammar Terms

The label affirmative is applied to a statement which contains no negative item.
I agree. (affirmative)
I don’t agree. (negative)

Other examples are:
Sugar tastes sweet.
Man is mortal.
Alice is an engineer.
Alice sipped her coffee.
I am working.
She is my sister.

Note that not is not the only negative word in English. Words like hardly, seldom, never, scarcely, none etc., are also considered as negative words.

Agent

An agent is the conscious and deliberate instigator of an action. For example, Alice is an agent in each of the following sentences:

Alice sipped her coffee.
Alice slapped Peter.
Alice sang a song.
Alice wrote a book.

In a passive sentence, the agent is the expression that says who or what an action is done by.
A book was written by Alice (agent).
This picture was probably painted by a child (agent).

Attributive

Adjectives placed before nouns are in attributive position.
I saw a beautiful girl.
The lazy boy was punished.
She is a clever girl.
He was a kind man.

Base

In word-formation, base is the form which is the direst source of another form.

For example, happy is the base for forming all of happily, unhappy and happiness, while unhappy is the base for forming both unhappily and unhappiness.