What are the keywords in the following sentence? a dog is the only things that can mend a crack in a broken heart .
crack, dog, heart, mend, thing

What are the keywords in the following sentence? a row of several rail road tracks at a station
row, station, track

What are the keywords in the following sentence? A dog leans over and sniffs a piece of concrete.
dog, piece, sniff

What are the keywords in the following sentence? An airport where aeroplanes are landed,one of which is Hawaiian.
aeroplane, airport, land