instruction:
In this task, find the most appropriate number to replace the blank (indicated with _ ) and express it in words.
question:
Cigarette smokers have up to a _ times higher incidence of bladder cancer than non-smokers.
answer:
four


question:
Knives have _ cutting edges for double cutting life.
answer:
two


question:
Cats have _ taboos about mating with siblings or even their offspring.
answer:

no