9. C
10. C
11. A I believe
12. D
I believe the first answer is The Turks captured Constantinople closing the path to the Silk Road. The second is Europeans developed the economic system of mercantilism and needed reserves of gold and silver. Hope I helped!
The Boeing B-29 was used by the United States Air Force towards the end of World War II, as well as in the Korean War. They were only produced from 1943-1946, right at the end of the war. However, they were used by the USAF and Royal Air Force until 1954. The entire line (including the revised version, the B-50) was retired in 1960.
Therefore, the answer is A, since production of the plane stopped in 1946, one year after the end of WWII.
