Type of floor that is durable, versatile and not easily pierced

Which article of the us constitution addresses the issue of interpeting the laws of the united states

What is generally true of the lower house in a state legislative branch ?

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?