统一是一个国家和民族的主流。我国历史上结束了南宋、西夏、金分裂，实现大统一的朝代是[ ]
A．秦朝
B．隋朝
C．元朝
D．清朝
C
若f（1，1）=1234，f（x，y）=k，f（x，y+1）=k-3，则f（1，2012）=（ ）
A．-4799
B．-6033
C．1235
D．2012
The city government is planning to build a factory to deal with the industry waste，but when and where to build it________.
A．haven’t been decided
B．aren’t decided
C．hadn’t been decided
D．hasn’t been decided
