Two wheeled vehicles are hard to see because...

What greek scientist created a screw to move water for irrigation?

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?

Which of these would be describing a developed country? a) literacy rate of 84% b) life expectancy of 58 years c) post-secondary education rate of 10% d) infant mortality rate of 3 per 1,000 births