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.

All cars are things that have ____ wheels.
four

Inhibited desire is the most common sexual dysfunction, effecting ____ in three couples.
one

Prosthodontists typically train for ____ years to learn the best ways to restore dental implants.

three