There were obvious difficulties in learning a new field and having to catch up to people who have been doing it all their lives. (science.sciencemag.org)
This serious condition needs immediate veterinary care if the bird is to survive — if your bird has obvious difficulty breathing, seek help immediately. (thesprucepets.com)
The most obvious difficulty is that rising pressure puts the squeeze on the lungs and any other air spaces in the body. (newscientist.com)