What are the keywords in the following sentence? fictional image of the moon and earth
earth, image, moon

What are the keywords in the following sentence? a stack of books makes me smile .
book, smile, stack

What are the keywords in the following sentence? aerial early morning shot of flying over the valley with heavy fog .
fog, shot, valley

What are the keywords in the following sentence? heavy thick smoke covering the sky as it billows up from a fire .
billow, fire, sky, smoke