命题“若一个数是负数,则它的平方是正数”的逆命题是[ ] A.“若一个数是负数,

题型:选择题

问题:

命题“若一个数是负数,则它的平方是正数”的逆命题是[ ]

A.“若一个数是负数,则它的平方不是正数”

B.“若一个数的平方是正数,则它是负数”

C.“若一个数不是负数,则它的平方不是正数”

D.“若一个数的平方不是正数,则它不是负数”

考点:四种命题及其相互关系
题型:选择题
下列图形中具有稳定性的是(  )
A.正方形B.梯形C.三角形
题型:选择题

C10和I10的换算关系是C10=()。

题型:选择题

新《商检法》的规定,凡列入《出入境检验检疫机构实施检验检疫的进出口商品目录》的进出口商品,海关凭()验放。

A.货物通关证明

B.商检机构签发的检验证书

C.商检机构在报关单上加盖的印章

D.商检机构签发的放行单

题型:选择题

全国银行间债券市场做市商应当履行的义务包括()

A、确定的做市券种总数应当不少于6种,且最终确定的做市券种应当包括政府债券、政府类开发金融机构债券和非政府信用债券3种类型

B、做市券种的期限应当至少包括0-1年、1-3年、3-5年、5-7年和7年以上等5个待偿期类型中的4个

C、做市商一旦确定做市券种后,当日不能变更,且应当对所选定的做市券种进行连续双边报价,双边报价空白时间不能超过30分钟

D、做市券种单笔最小报价数量为面值100万元人民币

题型:选择题

Dina Borzekowski made a study of a group of third-grade students from six American schools. During a school year, nearly 400 students and their parents were asked to report on whether they had such things as televisions and computers in the home, as well as how often the child used them. The children’s language ability was tested (测验) twice over the year. Children who had a television set in the bedroom but did not have a computer at home scored (得分) the lowest, while students without TV in the bedroom but with a computer at home scored the highest. Students who had a television in the bedroom over the school year scored lower than those who had their TV taken away during the same time.
"This study suggests that taking TV sets out of children’s bedrooms, or not putting them there, may be helpful," said Borzekowski. "While this study does not prove (证明) that bedroom TV was the reason for the lower test scores, it suggests that children shouldn’t have TV in their bedrooms. It also suggests that a home computer may help a child’s test scores. The best way was having both: no TV in the bedroom and also a home computer to use. \

How long did Borzekowski’s study last
[A] One year.
[B] Three years.
[C] Six years.

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