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: Seismologists offer ____ major theories for the occurrence of large, deep earthquakes.

A: three
****
Q: Birds have ____ beak, two wings, and two feet.

A: one
****
Q: Mechanical stability comes from having fused quartz, in ____ gravity, cold.

A:
zero
****