a dog
It is a dog.
a cat
It isn't a cat.
pencils
They are pencils.
rulers
They aren't rulers.
a teacher
He is a teacher.
a policeman
He isn't a policeman.
students
They are students.
teachers
They aren't teachers.
a giraffe
It is a giraffe.
a lion
It isn't a lion.
one year old
It is one year old.
three years old
It isn't three years old.
yellow
They are yellow.
pink
They aren't pink.
sad
He is sad.
happy
He isn't happy.
