Problem: What are the most important words?
the castle is located on a hill above the town shining through the morning fog
Answer: fog, hill, town

Problem: What are the most important words?
a pressed plant with green stems and leaves made up of many green leaflets .
Answer: leave, plant, press, stem

Problem: What are the most important words?
A dog is helping to herd the sheep for the farmer.
Answer:
farmer, help, herd, sheep