Problem: What are the most important words?
biological species is an extinct mammal that lived during geologic time period
Answer: live, mammal, specie

Problem: What are the most important words?
near a city we found this plant growing right along the sea shore .
Answer: find, grow, plant, shore

Problem: What are the most important words?
protesters clash with riot police during a protest
Answer:
clash, police, protest, protester