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: Ozone is formed of ____ atoms of oxygen.

A: three
****
Q: Fish kills can occur when oxygen is less than ____ ppm.

A: three
****
Q: Cougars have ____ different names.

A:
four
****