instruction:
In this task, find the most appropriate number to replace the blank (indicated with _ ) and express it in words.
question:
Most people see the world through _ types of visual-receptor cells.
answer:
four


question:
Babies usually wet the diaper at least _ times each day.
answer:
six


question:
Vertebrate hemoglobin consists of _ subunits, called polypeptide chains.
answer:

four