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

[EX Q]: Telescopes come in _ basic types - refractors and reflectors.
[EX A]: two

[EX Q]: Several countries appear to have _ islands at all.
[EX A]: no

[EX Q]: Eagles have eyesight _ times greater than the human eye.
[EX A]:
eight