Input: Identify the most salient words:

water flowing down the drain

Output: drain
flow
water

Input: Identify the most salient words:

humans during this period found shelter in caves .

Output: cave
find
human
period
shelter

Input: Identify the most salient words:

green grass and flowers on the pasture

Output: flower
grass
pasture

Input: Identify the most salient words:

armed force walks near soldiers during training .

Output:
force
training
walk