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: Natural ytterbium is a mixture of ____ stable isotopes, with seven other unstable isotopes known.

A: seven
****
Q: Cockroaches have six legs, ____ antennae and some have wings.

A: two
****
Q: Kinetic energy consists of ____ types of energies.

A:
three
****