What are the keywords in the following sentence? biological species caught and released by fly fisherman near person
catch, fisherman, release, specie

What are the keywords in the following sentence? standing at the bottom of escalators at station
escalator, stand, station

What are the keywords in the following sentence? trips over football player during the match .
match, player, trip

What are the keywords in the following sentence? a protester is arrested by riot police during a clash at shopping district .
arrest, clash, police, protester