Problem: What are the most important words?
A large aircraft parked on the runway in an airport
Answer: aircraft, airport, park

Problem: What are the most important words?
Giraffes are peeking out their heads by tall trees.
Answer: giraffe, head, peek, tree

Problem: What are the most important words?
astronaut in outer space on the elements of this image furnished by spacecraft manufacturer
Answer:
astronaut, furnish, image