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]: Gibberellins are diterpenoids derived from four isoprenoid units forming a system of ____ rings.
[EX A]: four

[EX Q]: Most spiders have eight eyes and ____ legs.
[EX A]: eight

[EX Q]: Smokers have two to ____ times the risk of nonsmokers.
[EX A]:
four