In this task, find the most appropriate number to replace the blank (indicated with _ ) and express it in words.

[EX Q]: Smokers die an average of six to _ years earlier than nonsmokers.
[EX A]: eight

[EX Q]: Tin exists in _ allotropic forms.
[EX A]: three

[EX Q]: Resonant converters are another example of _ voltage switching.
[EX A]:
zero