What are the keywords in the following sentence? image of the triple star listed as ngc
image, ngc, star

What are the keywords in the following sentence? kind doctor taking care of an old man in wheelchair .
care, doctor, take, wheelchair

What are the keywords in the following sentence? cars available for rent and for purchase at the dealership outside a city
car, dealership, purchase

What are the keywords in the following sentence? A cyclist gets towed by a motorcyclist gaining more and more speed on a racetrack.
cyclist, gain, speed