已知数列{an}的通项公式an=49-2n,则该数列的前n项和Sn取最大值时,n

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问题:

已知数列{an}的通项公式an=49-2n,则该数列的前n项和Sn取最大值时,n的取值为(  )

A.22

B.23

C.24

D.25

考点:等差数列的通项公式等差数列的前n项和数列的概念及简单表示法
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下列有关妇科腹部手术病人,术后引流管的护理内容应除外

A.随时观察引流液的性质和量

B.保持引流管通畅

C.引流瓶应隔日更换

D.引流管需要每日更换

E.每日测体温3次,以及早发现感染征兆

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上海人民广播电台发射一种电磁波的频率为990kHz,中央人民广播电台发射一种电磁波的频率是15.58MHz,对两广播电台发射的电磁波相比,以下分析中正确的是(  )

A.两台发射的电磁波,波速相同,上海台的波长长

B.中央台的波速大,两者的波长相等

C.中央台的波速大,上海台的波长长

D.两台发射的电磁波,波速相同,中央台的波长长

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Matt Haimovitz is 42 and a renowned cellist (大提琴手) in the world. He rushed into the classical music scene at the age of 12 after Itzhak Perlman, the famed violinist, heard him play.

But nothing in his family history explains where Haimovitz got his extraordinary talent. And that’s typical, Ellen Winner, a professor says.

“People are fascinated by these children because they don’t understand where their talent came from. You will see parents who say, ‘I wasn’t like this, and my husband wasn’t like this.’ It seems to sometimes just come out of the blue,” Winner says.

It’s not clear whether a prodigy’s (天才)brain is any different from the brains of other children, in part because there have been no study comparing the brains of prodigies to those of average people.

“But I believe that anything that shows up so early, without training, has got to be either a genetic or some other biological basis,” Winner says. “If a child suddenly at the age of 3 goes to the piano and picks out a tune and does it beautifully, that has to be because that child has a different brain.”

Children who are extremely gifted tend to be socially different, too, Winner says. “They feel like they can’t find other kids like themselves, so they feel strange, maybe even like a freak, and feel like they don’t have anybody to connect with. On the other hand, they also long to connect with other kids, and they can’t find other kids like themselves.”

As Haimovitz got older, he became frustrated. He wanted to play other kinds of music but felt constricted by the image and the expectations of the boy prodigy who played classical music and filled concert halls.

“When you start that early, you suddenly start to grow up in public, and I wanted to experiment,” Haimovitz says.

So he took his cello into punk rock clubs and coffee houses. He played Bach, Haydn and Hendrix. “My teacher was Leonard Rose, and we never played any 20th-century music. He didn’t like it. But once I was exposed to James Marshall “Jimi” Hendrix, Miles Dewey Davis El and others, I couldn’t really turn back. I wanted to know more,” he says.

小题1:According to some parents, prodigies’ extraordinary talent       .

A.comes unexpectedly

B.is inherited from parents

C.results from hard work

D.is trained in early times小题2:Winner seems to agree to the fact that ____.

A.average people have their particular brains

B.biology is the base of a different brain

C.a prodigy’s brain is superior to those of others

D.genes play an important role in a prodigy小题3:According to the text, gifted children are         .

A.lonely

B.easy-going

C.innocent

D.social小题4:The last paragraph is mainly about how Haimovitz was trying to         .

A.build up his friendship

B.play different kinds of music

C.set up the image of a prodigy

D.perform classical music creatively

题型:选择题

在电力系统中,()主要应用于三相三线制电网。

A、保护接零

B、保护接地

C、保护接相

D、保护设备

题型:选择题

下列不属于企业内部控制方式的是()。

A、内部价格

B、预算

C、奖罚

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