TASK DEFINITION: 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.
PROBLEM: China has about one in ____ of all smokers in the world.

SOLUTION: four

PROBLEM: Inversions have the classic double loop at meiosis, and have ____ crossovers when heterozygotes.

SOLUTION: no

PROBLEM: Plant cells have ____ major parts.

SOLUTION:
four