the answer is moon. the name tells you what you can't see. since in a solar eclipse you can't see the sun that means that the moon is in between us on earth and the sun. which is why we can't see it
If a scientist is studying an infectious agent in a lab, it is very important to understand the implications of evolution because then the scientist will be able to predict how the agent will adapt to different hosts.
I think the answer is Capilaries
Hope this helps
