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: Copper has ____ naturally occurring isotopes.

A: two
****
Q: Most organ systems are operational in the fetus by ____ to six months.

A: four
****
Q: Salsa is played in common time, that is ____ beats in every bar.

A:
four
****