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: Blood donors can give blood every ____ weeks, or six times a year.

A: eight
****
Q: Females become sexually mature at the age of ____ years.

A: five
****
Q: Today there are ____ major systems of naming herbs, including medicinal herbs.

A:
three
****