What are the keywords in the following sentence? silhouette of trees next to a frozen and snowy lake in the morning
lake, morning, tree

What are the keywords in the following sentence? the upper floors of the building partially covered in fog .
building, cover, fog

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

What are the keywords in the following sentence? A bathroom with a broken toilet full of brown stuff.
bathroom, stuff, toilet