instruction:
In this task, find the most appropriate number to replace the blank (indicated with _ ) and express it in words.
question:
Plankton has _ known ancestors.
answer:
two


question:
Germs have _ means of locomotion execpt to attach themselves to particles of dust.
answer:
no


question:
Exposure can occur in _ general ways, ingestion, skin contact and inhalation.
answer:

three