by injecting the weakened virus into your body it helps the body familiarize and create the right antiviruses for the virus so that if it ever gets in your system you can actually fight it.
hope that helps <3
Answer:
bcuz in which habit they have been addicted they can't change it easely after a long try also so it is hard to get people to change their behavior
Answer:
"Ecological niche is a term for the position of a species within an ecosystem, describing both the range of conditions necessary for persistence of the species, and its ecological role in the ecosystem."
Explanation:
sources: sciencedirect