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]: Inversions have the classic double loop at meiosis, and have ____ crossovers when heterozygotes.
[A]: no

[Q]: Giant pandas move on all ____ legs.
[A]: four

[Q]: Arthropods are made up of ____ groups of living animals and one group of extinct animals.
[A]:
four