Part 1. Definition
Given two noun phrases (arguments) and relationship between them, form a sentence that expresses theses arguments with the given relationship.
Part 2. Example
Relationship: 'knock', Argument/Subject 1: 'someone', Argument/Subject 2: 'it'
Answer: The mailbox was bent and broken and looked like someone had knocked it over on purpose.
Explanation: The generated sentence contains the two given subjects - someone and it, and they are related to each other on the basis of the given relationship - knocked
Part 3. Exercise
Relationship: 'join', Argument/Subject 1: 'croatium', Argument/Subject 2: 'european union'
Answer:

Show your work and conclude with the exact phrasing "Therefore, the final answer is [answer]." where [answer] is just the final number or expression that solves the problem.
user
All this happened 15 years ago and now Croatia is making good progress in its negotiations to join the European Union .