Reported to be the most terrifying to soldiers on the front because they often couldn’t see it.
a. chemical weapons
b. airplanes
c. submarines
d. machine guns

How did inca develop their road system? a) they used mortar to hold the stones together.b) they built suspension bridges over rivers. c) they mixed copper and stone together to make the blocks.d) they laid roads in the cities, not in the less densely populated deserts.