Relationship the interactions or connection between people 2.reciprocity point a view 3.efficiency equal exchange 4.perspective effective use of time

1. relationship = the interactions or connection between people
When two or more people are constantly interacting with each other, you can say they have a particular relationship between them. This relationship doesn't only have to be of romantic kind - it can refer to friendships, familiar relationships, it can be either close or not so close, etc.

2. reciprocity = equal exchange
The word reciprocity comes from Latin, where it meant 'moving backwards and forwards.' Over time, when the word was implemented into English, it got the meaning of a particular exchange between two or more parties, where each party gets the equal share.

3. efficiency = effective use of time
To be efficient means to use your time wisely. If you are efficient, it means that you are not wasting time on irrelevant things, but are rather taking advantage of the time you have in order to complete the things which are actually important. 

4. perspective = point of view
The terms perspective and point of view (both of which relate to the same thing) are often used in literature to denote the person who is telling that particular story. Perspective, or point of view, tell us whose story, thoughts, and feelings we are going to read the story from.