Given a sentence, fill out the missing word with a 'no' or a number (between zero and ten). You should write the numbers with english alphabet, like: four instead of 4.

Q: Knee arthroscopy is used basically in ____ ways.

A: three
****
Q: Biological islands are of ____ general types, geographical and ecological.

A: two
****
Q: Skin is composed of ____ layers.

A:
three
****