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]: Insects are identified by having ____ sets of paired legs, while isopods have seven.
[A]: three


[Q]: Herbs require at least ____ hours of sunlight.
[A]: six


[Q]: Photons do have ____ rest mass.
[A]:
zero