19. how did the song dynasty contribute to advances in transportation?

by inventing gunpowder
by inventing paper money
by inventing sail boats
by inventing the magnetic compass
20. how did nerva attempt to improve the roman economy?

he raised taxes on imports to increase trade.
he revised the banking and money systems.
he to control inflation by fixing prices.
he granted land to small farmers.
21. why did the chinese require the portuguese to pay for goods in gold and silver when trading?

the imperial government wanted to stockpile gold and silver.
portuguese and chinese currencies were not exchangeable.
portuguese goods were less valuable than chinese goods.
the chinese already had a surplus of portuguese goods.
22. why did the chinese silk trade die during the ming dynasty?

the chinese drove the silkworms to extinction by overusing them.
the europeans learned the process and could make their own silk.
the european desire for silk diminished and the demand was reduced.
the chinese used water routes, and silk could not travel over water.