What are the keywords in the following sentence? system of electric trains is extensive throughout the city .
city, system, train

What are the keywords in the following sentence? charcoal grey walls and silver accents in a moody modern living room
accent, room, wall

What are the keywords in the following sentence? The single donut is frying in the cooking grease.
donut, fry, grease

What are the keywords in the following sentence? Two young giraffes stand behind the gate of an enclosure.
enclosure, gate, stand