What are the keywords in the following sentence? passengers dragged baggage walking on the way at airport .
airport, baggage, passenger

What are the keywords in the following sentence? This train is parked under a bridge and stairwell.
bridge, park, train

What are the keywords in the following sentence? asphalt road among fields and forests .
asphalt, forest, road

What are the keywords in the following sentence? the city of biggest christmas tree yet is lowered into place on monday morning .
city, place, tree