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.

[EX Q]: Sexual reproduction involves the union of cells from ____ parents.
[EX A]: two

[EX Q]: Some species take ____ to two years, or even more.
[EX A]: one

[EX Q]: Thunderstorms are very dangerous, even when ____ tornadoes are formed.
[EX A]:
no