The purpose of this exercise is to train your abilities to distinguish between concepts and phenomena.
 Decide in each of the following cases if the mentioned item is a concept or a phenomena:
 - The door used to enter this room.
  - Todays issue of your favorite newspaper.
  - Your copy of today's issue of your favorite newspaper.
  - The collection of all copies of today's newpapers
  - Denmark.
  - European country.
  - The integer 7.
  - The set of integers between 1 and 10.
  - The set of all students who attend this course.
  - The oldest student who attend this course.
 
 For an item considered as a phenomenon, identify the underlying concept.