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: Couples spend ____ billion dollars a year on infertility treatments.

A: two
****
Q: Most people become sick ____ to seven days after infection.

A: two
****
Q: Light can go around the earth ____ times in one second.

A:
three
****