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]: Presidential elections take place every ____ years.
[A]: four


[Q]: Spiritual slavery comes in ____ forms.
[A]: two


[Q]: Human malaria is caused by ____ species of Plasmodium . .
[A]:
four