Why is there no definite article before loss and lack in examples 1 & 2, before people in 3 & 4, and before lands in 4?
- I'm suffering from loss of blood.
- New parents are suffering from lack of sleep.
- I know people who have seen ghosts.
- I'm so sorry for people who live in lands where there are no May flowers.
In these sentences loss, lack, people, and lands aren't referring to general concepts, they are specified – so why we don't see definite articles before them?