instruction:
In this task, find the most appropriate number to replace the blank (indicated with _ ) and express it in words.
question:
Most turbines have either _ or three blades.
answer:
two


question:
Architectural shingles are twice or _ times as thick as ordinary shingles.
answer:
three


question:
Dolphin are abundant and on fortunate days _ species are sighted.
answer:

four