2.
Which type of entity cannot exist in the database unless another type of entity also exists in the database, but does not require that the identifier of that other entity be included as part of its own identifier?

8.
In which of the following is a single-entity instance of one type related to many entity instances of another type?

9.
Which of the following refers to an entity in which the identifier of one entity includes the identifier of another entity?

10.
Which type of entity is related to two or more associated entities that each contain specialized attributes that apply to some but not all of the instances of the entity?