Why did european nations have to trade silver in exchange for chinese goods for centuries

According to the federal regulations, which of the following studies meets the definition of research with human subjects? a. a researcher uses the customs office’s passenger lists for ships bringing immigrants to the us between 1820-1845 to track the numbers of immigrants from certain ethnic groups. b. a researcher conducts a linguistic study of comments posted on a local public blog. c. a developmental psychologist videotapes interactions between groups of toddlers and their care givers to determine which intervention methods most effectively manage aggression. d. a researcher asks the director of a local free clinic about the number of patients in the last two years with newly diagnosed hiv/aids.

On a supply and demand graph, equilibrium is the point where the two curves meet. the supply curve begins. the supply curve ends. the demand curve ends.

How did ancient civilizations develope its agriculture and protect its population