I've seen this question asked many times but there are so many particularities that I did not find an anwser to my case. I'm a french student writting a science speech, and I hesitate between writing :
- ... used to map the dolphin's absence...
- ... used to map the absence of the dolphin...
and I have the same problem with :
- ... recorded the size of the groups of dolphins
- ... recorded the size of the dolphins'groups.
Thank you very much, and have a nice day !