Problem: What are the most important words?
An electric engine pulls a long train of cargo cars.
Answer: car, engine, pull, train

Problem: What are the most important words?
football player applauds the fans at the final whistle
Answer: applaud, fan, player, whistle

Problem: What are the most important words?
a commercial herd of cattle eat hay during the winter
Answer:
cattle, eat, hay, herd