instruction:
In this task, find the most appropriate number to replace the blank (indicated with _ ) and express it in words.
question:
Prolactin exists in _ heterogenic forms which possess varying biological activity.
answer:
three

question:
Comets are a bit like giant dirty ice-balls with diameters between _ and fifty kilometres.
answer:
five

question:
Most children have a vocabulary of eight to _ words, including names, by eighteen months of age.
answer:
ten