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: Success is a function of ____ things.

A: two
****
Q: Rabbits have ____ incisors in the upper jaw where rodents have only two.

A: four
****
Q: Free trade exists only where there are ____ barriers to voluntary exchange.

A:
no
****