Jonas salk was awarded the nobel prize for discovering a way to vaccinate against polio in the united states in the 1950's. this allowed millions of school-age children to avoid a crippling disease, and to swim during summer again, as polio was often spread in public swimming areas before. which statement most closely describes how the polio vaccine works?

Johnny rode his bike to a friend's house 4 blocks down the street in his neighborhood. he immediately rode back home once he realized his friend was not able to play. what was his displacement for the total bike ride? how did you determine this? what could we use as a reference point to determine he was in motion during his bike ride? why can you use it as a reference point

What type of pollution does household garbage cause

Land conservation is a worldwide priority. there are several methods to prevent the loss of land due to a variety of reasons. which method is not a way to conserve land? a) sea walls b) rainwater harvesting c) limits on clear cuts of forests d) cut and burn methods of clearing land