Problem: What are the most important words?
this dredge project started at a site that has no natural flowing source of water .
Answer: project, source, water

Problem: What are the most important words?
An elephant next to a herd of zebra by a watering hole.
Answer: elephant, hole, zebra

Problem: What are the most important words?
A man is making sandwiches by placing slices of cucumbers and tomatoes on the bread.
Answer:
cucumber, sandwich, slice, tomato