In this task, find the most appropriate number to replace the blank (indicated with _ ) and express it in words.

Q: Birds bitten by infected mosquitoes are infectious from _ to eight days.

A: four
****
Q: All insects have _ pairs of legs and adult wings.

A: three
****
Q: Casein proteins have _ major types, and all three appear in every mammal species on Earth.

A:
three
****