Problem: What are the most important words?
aircraft model leads a parade of emergency vehicles
Answer: lead, parade, vehicle

Problem: What are the most important words?
fresh tuna lies awaiting inspection and auction the worlds largest daily fish market
Answer: inspection, lie, market, tuna, world

Problem: What are the most important words?
A fishing lure is shown close up while a man ties it and explains how to do it.
Answer:
explain, lure, tie