Problem: What are the most important words?
one of many smaller waterfalls cascading down the mountain .
Answer: cascade, mountain, waterfall

Problem: What are the most important words?
red boat moored beside small house by a canal
Answer: boat, canal, house, moor

Problem: What are the most important words?
flock of sheep and goats grazed on open spaces .
Answer:
goat, graze, sheep