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: Mammals have ____ cervical vertebrae, a number that remains remarkably constant.

A: seven
****
Q: Potential energy is divided into ____ different types of energy.

A: three
****
Q: All vegetative cells contain ____ sets of chromosomes.

A:
two
****