What are the keywords in the following sentence? nobody can fully understand love unless they are owned by a dog .
dog, love, understand

What are the keywords in the following sentence? passengers leaving a train on a station
leave, passenger, station, train

What are the keywords in the following sentence? A van is parked next to a fire hydrant.
hydrant, park, van

What are the keywords in the following sentence? mother and father using both hands to make a heart over their unborn child
hand, heart, mother