Business English - Confused in the work place

There are some words related to work that can be very confusing, as they sound similar but have very different meanings. For example:

Employer- the person who employs people (the boss).
Employee- the person who works for the employer.

Or sometimes, the words don't sound the same, but the meaning can be fairly similar.
E.g.
Retire- to leave your job after working a long period of time.
Quit - to leave your job for other reasons e.g. you don’t like your boss.

In the following sentences, which word fits in the sentence? Can you give a brief explanation of each word used?

Today's lesson is by Caroline

Link: Business English: the language of 'business meetings'

• 1. My ___ doesn't listen to staff when they have problems.
  
  employer
  employee
  
  
• 2. All ___ should work together to achieve the goals of the company.
  
  employees
  employer
  
  
• 3. I think I am going to ___when I am sixty five and go to Spain.
  
  retire
  quit
  
  
• 4. I'm really not enjoying my job at the moment. I want to ___.
  
  quit
  retire