What are the keywords in the following sentence? little blue flowers growing from a crack in concrete
concrete, crack, flower, grow

What are the keywords in the following sentence? aircraft on the runway of the airport
aircraft, airport, runway

What are the keywords in the following sentence? car decorated with ribbons at a wedding
car, ribbon, wedding

What are the keywords in the following sentence? A train engine and several cars moving along a track in a city.
car, engine, move