不定项选择
对于每个集合
, 
。
A．正确
B．错误
对于每个集合
, 。
A．正确
B．错误
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单项选择题
In which year the world's population lived in urban areas is more than 50% for the first time in history?
In which year the world's population lived in urban areas is more than 50% for the first time in history?
A．2007
B．2000
C．2010
D．2005
A. 
B. 
D. 