instruction:
In this task, find the most appropriate number to replace the blank (indicated with _ ) and express it in words.
question:
Carbon dioxide extinguishes fire by physically attacking all _ points of the fire triangle.
answer:
three

question:
Telescopes come in _ basic types - refractors and reflectors.
answer:
two

question:
Ozone leaves _ by-products except pure oxygen.
answer:
no