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问题 单项选择题

在常用的几种抽样方法中，最便于组织，并且节省经费的是（）

A．单纯随机抽样

B．分层抽样

C．整群抽样

D．机械抽样

E．单纯随机抽样和机械抽样

答案

参考答案：C

判断题

库伦土压力理论假设墙后填土填土中的滑动破裂面是平面，且通过墙踵。
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单项选择题

Spyware and other forms of malware are the biggest online threat to your computer's （） nowadays. These malicious （） which get to your PC through freeware, shareware, commercial sites, deceptive pop-ups or in any other way, can record your surfing habits and sites you visit, share your personal information with their partners. Any personal （）, when in wrong hands, can leave you a victim of an "identity theft" by steeling your credit （）details, birth records and other （） information.

Spyware and other forms of malware are the biggest online threat to your computer's （） nowadays.

A. reliability

B. security

C. capability

D. efficiency
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