instruction:
In this task, find the most appropriate number to replace the blank (indicated with _ ) and express it in words.
question:
Premolars have one, two, and sometimes _ canals.
answer:
three


question:
Armaments manufacturers use lithium to produce tritium in _ ways.
answer:
two


question:
Malnutrition affects three times more children under _ in the countryside than in the towns.
answer:

four