题干

对于函数y=f(x),若存在定义域D内某个区间[a,b],使得y=f(x)在[a,b]上的值域也是[a,b],则称函数y=f(x)在定义域D上封闭,如果函数f(x)=
k
x
1
+
x
2
(k≠0)在R上封闭,那么实数k的取值范围是____
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(﹣∞,﹣1)∪(1,+∞)

同类题3

阅读理解

    Filmmaker Jennifer Nelson had to pay $1,500 to have “Happy Birthday to You” sung in the movie she's making. The money went to Warner Music Group, a company that claims to own the copyright on the song. A copyright is the legal right to use or sell a creative product such as a song, a TV show, a book, or a work of art. Warner has claimed the copyright for “Happy Birthday to You” since 1988.

    “I never thought the song was owned by anyone,” Nelson said in an e-mail to The New York Times. “I thought it belonged to everyone.”

    Nelson's movie is a documentary — a film that uses pictures and/or interviews with people to create a factual report of real-life events — and is actually about the history of the “Happy Birthday” song itself.

    Two sisters named Mildred and Patty Hill wrote a song called “Good Morning to All” in 1893. Over a short period of time, people began to sing the words “happy birthday to you” in place of the original lyrics to the tune of the Hill sisters' song.

    A number of history experts say that there is no record of who actually wrote the “Happy Birthday to You” lyrics. Historians also say there is no way to know when the general public began singing the “Happy Birthday” song, but they believe it was being sung by the public long before it was printed and owned by a company.

    Nelson's lawyers say this piece of music's history proves that “Happy Birthday to You” belongs to everyone in the general public. That would mean Warner Music Group has no right to charge anyone a fee to sing the song in any setting.

    Experts estimate that Warner/ Chappell, the publishing division of the Warner Music Group, has made about $2 million a year from licensing fees for “Happy Birthday to You.”

    Nelson's lawyers are asking a court in New York City to order Warner/Chappell to return fees they have collected over the past four years for use of the “Happy Birthday” song.

同类题4

在经济发展过程中,常常会出现经济“调整(或退却)”的现象。阅读下列材料:

材料一  内战的结束意味着不再需要……这种权宜政策,于是它被立即摒弃了。农民们拿起武器,反对无偿的征收。注重实际的列宁认识到让步是不可避免的,因而于1921年采取了,这一政策允许部分地恢复资本主义。对列宁来说,这种新的经济政策并不意味着社会主义在俄国的结束,而是暂时的退却,“后退一步为的是前进两步”。

——(美)斯塔夫里阿诺斯《全球通史》

材料二  我们必须退却,而要诚实地面对我们国家今天所遇到的形势。这个伟大的国家将坚持下,并将获得新生和繁荣……这个国家需要行动,而且现在就行动起来。

——罗斯福就职演说(1933年3月4日)

材料三  在那些边远山区和贫困落后的地区,长期吃粮靠返销,生产靠贷款,生活靠救济的生产队,群众对集体丧失信心,因而要求包产到户的,应当支持群众的要求,可以包产到户,也可以包干到户,并在一个较长的时间内保持稳定。就全国而论,在社会主义工业、社会主义商业和集体农业占绝对优势的情况下,在生产队领导下实行包产到户是依存于社会主义经济,而不是脱离社会主义轨道的,没有复辟资本主义的危险,因而并不可怕

——《中共中央关于进一步加强和完善农业生产责任制几个问题的通知》(1980年)

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