In this task, find the most appropriate number to replace the blank (indicated with _ ) and express it in words.
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Question: Triaxial fabric is woven with _ sets of yarn whose intersections form equilateral triangles.

Answer: three

Question: Gravity is the weakest of all _ forces but unlike the others it has an unlimited range.

Answer: four

Question: Most healthy men experience about _ to five erections in their sleep each night.

Answer:
three