问题
单项选择题
某县为一肝癌高发区，在该县随机调查一个乡进行肝癌死亡回顾性调查，属于（）
A．单纯随机抽样
B．分层抽样
C．整群抽样
D．多级抽样
E．系统抽样
答案
参考答案：C
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某县为一肝癌高发区，在该县随机调查一个乡进行肝癌死亡回顾性调查，属于（）
A．单纯随机抽样
B．分层抽样
C．整群抽样
D．多级抽样
E．系统抽样
参考答案：C
My uncle had a small farm. He also worked in a . One autumn, he promised to help his neighbor harvest(收割) their corn（玉米）. , after harvesting their corn, my uncle’s little machine broke. the same time, the factory where Uncle worked began to work for more hours. He had to leave the farm early in the morning and didn’t get home until very late. It now seemed to help out his neighbor. But my uncle decided to do it by hand. One night, after working all day in the factory, my uncle went to the neighbor’s farm and the work under the bright moon. My uncle kept his promise. He also taught me an important lesson: keeping a promise is more important than making it.
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