An astrolabe is a primitive angle-measuring tool. It can be used to - very in-exactly! - measure the altitude above the horizon of a celestial body like the Sun, Moon or Polaris in order to calculate your position.
Medieval gunners used the astrolabe to calculate the height of towers and buildings, in order to more accurately aim their cannons.
C. Three equal branches with different powers
The Opium Wars were a series of wars between Chine and Great Britain. It started when Chine started to refuse the shipments of Opium. The war was a fail for China, this means that answer A, C, and D are wrong. The only answer left is B. Please contact me if you want more information on the opium war.
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In the review, the writer keep using the word 'we' such in : "we doubt Mrs. stowe would recognize the cogency of this argument"
Ferries, trains, and planes