题干

①“∃x∈R,x2﹣3x+3=0”的否定是真命题;

②“

1
2
<x<0 ”是“2x2﹣5x﹣3<0”必要不充分条件;

③“若xy=0,则x,y中至少有一个为0”的否命题是真命题;

④曲线

25
x
2
+
y
2
9
=1 与曲线 25
x
2
k
+
y
2
9
k
=1(9<k<25)
有相同的焦点;

⑤过点(1,3)且与抛物线y2=4x相切的直线有且只有一条.

其中是真命题的有:____(把你认为正确命题的序号都填上)

上一题 下一题 0.0难度 选择题 更新时间:2019-08-09 11:45:36

答案(点此获取答案解析)

①③④

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近几年,地震活跃频繁。对此,有关专家指出:“地球其实一直处于‘震动’状态,‘震动’是地球的常态。”从现有研究水平来看,根据己有的历史地震资料进行中长期的地震预报是完全可能的。该材料蕴含的哲理是(    )

①量变是质变必要准备

②运动是物质的唯一特性

③运动是物质固有的根本属性和存在方式

④思维与存在具有同一性

同类题2

如图,抛物线y=﹣x2+bx+c交x轴于点A(﹣3,0)和点B,交y轴于点C(0,3).

同类题3

判断题.

3能被3整除.

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下列哪种疾病不是由链球菌引起的 (     )

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阅读理解

    I set out to change the lives of those who need help by joining my school's newly formed Free The Children Club. Through the determination of friends, the group has grown bigger and stronger each year. Over the past two years my friend, Alex Auclair, and I have become the leaders of the club.

    Already, after only two years of fundraising, we have accumulated over three thousand dollars and almost two thousand food items through various fundraising efforts. For example, each year a 24-hour famine (饥饿) is planned resulting in absolutely no consumption (消耗) of food. By taking part in these activities, we put ourselves in the shoes of someone living in poverty.

      No money raised goes to waste. At the end of each school year, the group takes a vote to determine where our funds will be spent and donated. Last year, we bought enough desks, chairs, supplies and textbooks for every student in a Kenyan school. This year, we plan to spend our earning helping out families in Sierra Leone.

    Poverty is a worldwide issue affecting the lives of people in not only developing countries, but also first-world countries such as Canada, the United Kingdom and Japan. Living in poverty can result in hunger, many forms of disease, lack of education, and for millions, death. It does not have to be this way. You too can form a club like the Free The Children Club or you can participate in events outside of school. Get your friends, family, even your community involved in fundraising. Do what you can to change the world.

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