What's this?
Common Cold
What's this?
infect
What's this?
swallow
What's this?
virus
What's this?
mucus
What's this?
bacteria
What's this?
paralyzed
What's this?
disease
What's this?
influenza
What are these?
cells
What's this?
microscope
What's this?
scrape
What's this?
immune