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【单选题】
对用户而言,操作系统的真正安全风险在于(第9章305)A.
系统存在安全漏洞
B.
没有加密措施
C.
用户缺乏安全意识
D.
可以远程加载
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反馈参考答案：
举一反三
【单选题】下列说法正确的是（ ）
A.
若|a|=-a，则a＜0
B.
若a=b，m是有理数，则 a m = b m
C.
若a＜0，ab＜0，则b＞0
D.
式子3xy 2 -4x 3 y+12是七次三项式
【单选题】下列命题中真命题是（ ）
A.
若a≠0，则a -1 ＜a
B.
若a＞b，则|a|＞|b|
C.
若sinα= 1 2 ，则α=30°
D.
若a≠b，则（a-b） 2 ＞0
【简答题】第四章测试题.wps
【单选题】下列各式中，变形正确的是（ ）
A.
若a=-2（b-2），则a=-2b-4
B.
若-2x≥4a，则x≥-2a
C.
若 1 2 a+ 1 3 b=1 ，则3a+2b=1
D.
若a=b，则a+c=b+c
【单选题】Which of the following statements about American basketball culture is not correct?
A.
Basketball was invented in early December 1891 by James Naismith, an American physical education teacher.
B.
In the American basketball culture, there are roughly three kinds of basketball forms that can represent the United States.
C.
American basketball culture is a kind of sports that takes health care, skill and performance as the basic mode and advocates etiquette, generosity and peace.
D.
The Golden State Warriors won the 2018 NBA championship.
【简答题】Marie could hardly recognize the office she went into as _______.
【简答题】Once a small boy lived on a farm which seemed so far away from everywhere. He needed to get up before sunrise every morning to help his father on the farm. During sunrise he would take a break and cli...
【单选题】已知a，b∈R，命题“若a+b=1，则 a 2 + b 2 ≥ 1 2 ”的否命题是（ ）
A.
若 a+b≠1，则 a 2 + b 2 ＜ 1 2
B.
若 a+b=1，则 a 2 + b 2 ＜ 1 2
C.
若 a 2 + b 2 ＜ 1 2 ，则a+b≠1
D.
若 a 2 + b 2 ≥ 1 2 ，则a+b=1
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