Student or Learner
When do we use" Doing" ..normally we use it to indicate that we are doing something but in following sentence I find it different Please check this and elaborate on the usage of doing :
1) I had a tough time doing these/the exam (Can we also use writing instead of tough in 1st and 2nd sentence)
2) I was doing my exams when you called
Also is the follwoing sentene if my exams are already over last week and if I am saying this sentence after that to my friend then should I say "These" or "The" exams and why?