What do the following geographical features covers almost half of the African continent

Articles of the confederation is a good representation of a system of government.

What makes water a renewable source

Chen's research team randomly assigned some newborns and their mothers either to a breastfeeding promotion group (where breastfeeding was encouraged, but not required) or to a normal pediatric care group (where breastfeeding was neither encouraged nor discouraged). which research method did they use?