- What was going on in my absence.
- What has been going on in my absence.
This is a task on translating. There is no other context. I want to kno what is the difference.
The first one means that there was some period of time between the moment of spmeone's arriving and asking for information (came back yesterday; two days left; wanted to know about the last changes happened), doesn't it?
The second means that the someone asking this question has just came back and want to know about things happened. The the process of "going on" is connected with the present time, current moment (for example, a company of your friends is sitting in your home and laughing about something).