1310nm/KM衰减为多少?1550nm/KM衰减为多少?一个熔接点插入损耗为多少

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问题:

1310nm/KM衰减为多少?1550nm/KM衰减为多少?一个熔接点插入损耗为多少?一个接头的插入损耗为多少?

考点:有线电视机线员有线电视机线员题库
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阅读理解。

     The idea for a science experiment can come from an unusual place. After watching a YouTube video of a dancing bird named Snowball, a scientist in California decided to study the ability of animals to keep the beat.

     Bird lovers have long claimed that their pets have rhythm, and there are many videos of dancing birds

online. Until now, scientists have suspected that humans are the only animals that can accurately keep

rhythm with music.

     Thanks to Snowball, that scientific opinion is changing. Snowball is a cockatoo, a kind of parrot, and

his favorite song is "Everybody" by the Backstreet Boys. When he hears the song, he moves his feet and

rocks his body with the tempo, or pace of the music, as though he is the only bird member of the boy

band.

     Aniruddh Patel is a neuroscientist, or a scientist who studies how the brain and the nervous system

contribute to learning, seeing and other mental abilities. He works at the Neurosciences Institute in San

Diego. After seeing Snowball' s dance online, Patel visited the cockatoo at the bird rescue facility he's

called home for two years. The scientist played "Everybody" for Snowball and also played versions of the song that were sped up or slowed down.Sometimes, Snowball danced too fast or too slowly. Often, when there was a change in tempo, Snowball adjusted his dancing to match the rhythm.In other experiments,

scientists have observed the same abilities in preschool children.

     Patel isn't the only scientist who has studied Snowball's moves. Adena Schachner, who studies

psychology at Harvard University, also wanted to know more about the dancing bird.Schachner's team

played different musical pieces for Snowball and a parrot named Alex, as well as eight human volunteers.

The scientists observed that the birds and the humans kept time to the music with about the same accuracy.

     Schachner and her team watched thousands of YouTube videos of different animals moving to music.

Not all the animals could dance, however.From watching the videos, the scientists observed that only

animals that imitate sounds, including 14 parrot species and Asian elephants, accurately moved in time to

music. 

1. The underlined words 'that scientific opinion" in the third paragraph refer to the theory that _____.

A. birds like Snowball have the ability to keep the beat

B. humans are the only animals that can accurately keep rhythm with music

C. the brain and the nervous system contribute to some mental abilities

D. bird pets can have their special rhythm under human’s instruction

2. From the fourth paragraph we may know that _____.

A. Patel is the only scientist who has studied Snowball’s moves.

B. Snowball is able to adjust his dancing to match the rhythm.

C. Snowball cannot dance to the versions of the song Everybody.

D. it is the brain and the nervous system that control the mental abilities.

3. The idea of studying animals' ability to keep the beat comes from _____.

A. bird lovers' discovery  

B. humans'  musical sense

C. the same abilities in children  

D. videos of dancing birds

4. According to the scientists, Snowball's ability to dance to music is probably related to the fact that

_____.

A. it is the only bird member of the Backstreet Boys band

B. it has the ability to imitate sounds

C. it is a kind of dancing parrot

D. it has the same abilities as preschool children

题型:问答题 简答题

关于加密技术,下列哪种说法是错误的

A.对称密码体制中加密算法和解密算法是保密的

B.密码分析的目的就是千方百计地寻找密钥或明文

C.对称密码体制的加密密钥和解密密钥是相同的

D.所有的密钥都有生存周期

题型:问答题 简答题

设备调试阶段要求调试人员严格按照规范标准进行,()全程进行监督旁站,并形成()文件。

A.项目总监;工程中间检查记录表

B.监理员;设备工程预验收检查表

C.单项负责人;电源隐蔽工程签证记录表

D.项目经理;监理工程师通知单

题型:问答题 简答题

1949年3月,在新中国即将诞生前夕,毛 * * 同志就告诫全党同志:“中国的革命是伟大的,但革命以后的路程更长,工作更伟大,更艰苦。这一点现在就必须向党内讲明白,务必使同志们继续地保持()的作风,务必使同志们继续地保持()的作风。”

题型:问答题 简答题

行车前检查各机构必须处于()。

A.原始位置

B.中间位置

C.终端位置

D.都可以

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