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By the time of the Uruk period (c. 4100–2900 BC calibrated), the volume of trade goods transported along the canals and rivers of southern Mesopotamia facilitated the rise of many large, stratified, temple-centered cities (with populations of over 10,000 people) where centralized administrations employed specialized workers. It is fairly certain that it was during the Uruk period that Sumerian cities began to make use of slave labor captured from the hill country, and there is ample evidence for captured slaves as workers in the earliest texts. Artifacts, and even colonies of this Uruk civilization have been found over a wide area—from the Taurus Mountains in Turkey, to the Mediterranean Sea in the west, and as far east as central Iran.
Who employed many laborers in the cities?
A: unanswerable

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Psychoactive drugs can impair the judgment of time. Stimulants can lead both humans and rats to overestimate time intervals, while depressants can have the opposite effect. The level of activity in the brain of neurotransmitters such as dopamine and norepinephrine may be the reason for this. Such chemicals will either excite or inhibit the firing of neurons in the brain, with a greater firing rate allowing the brain to register the occurrence of more events within a given interval (speed up time) and a decreased firing rate reducing the brain's capacity to distinguish events occurring within a given interval (slow down time).
The level of what is the reason stimulants and depressants change human perceptions of neurons?
A: unanswerable

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Both the Shanghai Stock Exchange and the Shenzhen Stock Exchange suspended trading of companies based in southwestern China. Copper rose over speculations that production in southwestern China may be affected, and oil prices dropped over speculations that demand from China would fall.
What natural resource dropped in value?
A: oil

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The Premier League has the highest revenue of any football league in the world, with total club revenues of €2.48 billion in 2009–10. In 2013–14, due to improved television revenues and cost controls, the Premier League had net profits in excess of £78 million, exceeding all other football leagues. In 2010 the Premier League was awarded the Queen's Award for Enterprise in the International Trade category for its outstanding contribution to international trade and the value it brings to English football and the United Kingdom's broadcasting industry.
Which Award is presented for outstanding contribution to national trade?
A:
unanswerable