What are the keywords in the following sentence? a terraced house is joined to the houses on either side of it by shared walls .
house, share, side, wall

What are the keywords in the following sentence? other shelves hold a collection of heels .
collection, hold, shelf

What are the keywords in the following sentence? The worker is putting shingles on the roof.
roof, shingle, worker

What are the keywords in the following sentence? pedestrians walk toward roman structure
pedestrian, structure, walk