At the same time as Crest, the first fluoride toothpaste, was getting recognition from the American Dental Association, cities were trying to add fluoride to their drinking water.
(cities; were trying; to add fluoride to their drinking water) Context(cities were trying,List([120, 138))):(cities; were trying to add; fluoride; to their drinking water)
cities were trying,List([120, 138))
cities cities
were trying were trying to add
to add fluoride to their drinking water
fluoride to their drinking water