设集合Pn={1,2,…,n},n∈N*,记f(n)为同时满足下列条件的集合A的

题型:解答题

问题:

设集合Pn={1,2,…,n},n∈N*,记f(n)为同时满足下列条件的集合A的个数:

①A?Pn;②若x∈A,则2x?A;③若x∈A,则2x? A。

(1)求f(4);

(2)求f(n)的解析式(用n表示)。

考点:分段函数与抽象函数集合的含义及表示
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治疗脾胃气虚型厌食首选方剂是()

A.保和丸

B.不换金正气散

C.异功散

D.养胃增液汤

E.曲麦枳术丸

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《经济日报》载文指出,要调高个人所得税起征点,减少国民税收负担,提高个人可支配收入;继续增加城镇低收入居民的收入,建立健全宽范围、多层次的社会保障网络。上述措施对扩大消费是有利的,因为 ( )

A.它有利于改善居民消费的心理预期

B.它能促进经济增长

C.它能为居民提供更多的消费品

D.它可以刺激消费品生产

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物流清单是多层次和树状结构的,其最长的一条加工路线就决定了产品的加工周期。

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在智力的研究上,古希腊唯物主义思想家毕达哥拉斯提出脑为()的住所

A.智慧

B.心灵

C.理智

D.行为

题型:解答题

More than 40 million Americans between the ages of 5 and 18 attend schools throughout the United States. About 2 million school-age children are taught at home. While home schooling offers an alternative to the school environment, it has become a controversial issue.

Many public school advocates take a harsh attitude toward home schoolers, perceiving their actions as the ultimate slap in the face of public education and a damaging move for the children. Yet, as public school officials realize they stand little to gain by remaining hostile to the home-school population, the hard lines seem to be softening a bit. Some public schools have moved closer to tolerance, and,even in some cases, are seeking cooperation with home schoolers. " We are becoming relatively tolerant of home schoolers. Let’s give the kids access to public school so they’ll see it’s not as terrible as they’ve been told, and they’ll want to come back, " says John Marshall, an education official.

Perhaps, but don’t count on it, say home-school advocates. Some home schoolers oppose that public school system because they have p convictions that their approach to education—whether fueled by religious belief or the individual child’s interests and natural pace—is best. Other home schoolers contend " not so much that the schools teach heresy, but that schools teach whatever they teach inappropriately." "These parents are highly independent and strive to ’take responsibility’ for their own lives within a society that they define as bureaucratic and inefficient. " says Van Gallon.

But Howard Carol, spokesman for America’s largest teachers union, argues that home schooling parents are trying to hide their children from the real world, says Van Gallon. " Maybe we are going to run into people with problems, people that have a drug problem, people that have an alcohol problem, and teenage pregnancy. We have many problems that happen in our society and many of the children are victims. But shielding the children from the real mix of what happens every day is denying them something that they are going to need later in life. " Mr. Carol also questioned the competence of parents as teachers though he admitted that some home schoolers do better academically. " We want to make sure that a student is not denied the full range of curriculum experiences and appropriate materials, especially now with the new technology that is being introduced and the costs involved there. "

" The success of home schooling has been documented in standardized test scores administered by public school officials, " says Frank Bernet, the executive director of the National Association of College Admission Councilors. " I know why they are doing it, but I wonder why they can’t work with school officials and teachers to make the school what they want it to be. " The response from home schoolers: " We have tried that. NOW it’s time to strike out on our own. \

Public schools are softening their position on home schooling because()

A. they have come to realize the futility of the hard line

B.they have benefited from cooperation with home schoolers

C.home schooling has some advantages in teaching

D. children should be given chances to go back to school

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