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]: Tall fescue produces the ____ diazaphenanthrene alkaloids, perlolidone and perloline.
[EX A]: two

[EX Q]: Amphibians have ____ legs, and often look like reptiles.
[EX A]: four

[EX Q]: World history is presented as ____ discrete periods, from pre-history to the present.
[EX A]:
six