Problem: What are the most important words?
biological species searches the water for a small meal .
Answer: search, specie, water

Problem: What are the most important words?
A scientist is doing a tutorial explaining the germs of a handshake.
Answer: explain, handshake, scientist

Problem: What are the most important words?
police trying to prevent the passage of citizens who did queuing to vote
Answer:
citizen, police, prevent, vote