Problem: What are the most important words?
defensive tackle american football defensive tackle moves in to sack american football player during the first half .
Answer: football, player, sack

Problem: What are the most important words?
spacecraft manufacturer and country are going to work together on a new space station by the moon
Answer: country, moon, station

Problem: What are the most important words?
a secretary closes her desk and leaves for the day .
Answer:
close, day, leave