What was the first commercial photography process?

Which four of these developments were made under mongol rule during the pax mongolica? the extension of the grand canal in china the spread of christianity the spread of weapons that used gun powder the invention of new medicines the establishment of a postal system the invention of geometric models of lunar motion

In an economic downturn, what can happen in countries that depend on high taxes to fund social programs?

Why did the united states pass the neutrality acts