How can a president send troops into combat without congressional approval?

How and why has british society changed over the last 50 years?

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?

How did ancient civilizations develope its agriculture and protect its population