#1) Koryo built a wall at the Yalu River in the eleventh century to help keep out what enemy?
Answer: The reason why koryo built a wall at the Yalu River in the eleventh century was to help keep out Khitans. Out all the options A) is the correct choice.
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millions of troops needing jobs
labor unions going on strike
another major economic depression
British colonization happend because due to economic reason such as inflation. Others came because to seek religion freedom and improved living conditions
Answer: Rivers provided both fresh water and good soil.
The answer is B. the clock
the clock was invented hundreds of years before he was born