单选题Decibel is______.A the unit for measuring the intensity of soundB the pressure of radiating wavesC the frequency of radiating wavesD the seed of sound

题目
单选题
Decibel is______.
A

the unit for measuring the intensity of sound

B

the pressure of radiating waves

C

the frequency of radiating waves

D

the seed of sound

相似考题

1.English words are not always spelt in the way .A.they soundB.that soundC.it soundsD.how to sound

2.You are located within a stationary high pressure area．Your aneroid barometer is falling very slowly．This indicates a（n）______．A.Wind shift of 180°B.Large increase in wind velocityC.Decrease in the intensity of the systemD.Increase in the intensity of the system

3.共用题干 第二篇The Magic of SoundMusic is one of the most beautiful forms of artistic expressions ever invented.In movies and plays, music has an added function:it not only moves people but also can shock people.Our eardrums can withstand sound within 20 to 80 decibels（分贝）.Once sound exceeds this limit , even beautiful music will become ear-splitting noise and harm health.A strong blast（响声）of high sound can twist and break a solid iron sheet.High sound of 150 decibels can kill a healthy rat.In movies,sometimes the hero can produce a sound that ordinary people can't hear and only those whohave the same ability can feel.In nature,there is actually sound that is beyond our hearing.In physics,the sound that exceeds 20,000Hz is called ultrasonic（超音波的）.Dolphins, whales and bats can make such high-frequency sound.It does no harm to health.Sound less than 20Hz is called infrasonic（次声）waves.When we move, the air will vibrate.The vibration of air can produce infrasonic waves.As the frequency of infrasonic waves is close to that of people's internal organs, infrasonic wave may cause resonance（共振）in human bodies.As a result,people's vision may weaken and internal organs may rupture（断裂）.However,whether an infrasonic wave can be used as a weapon depends on its intensity.If its intensity is very low,it won't damage internal organs or a person's health.If the intensity of infrasonic wave exceeds 160 decibels,it is extremely harmful.When wind blows at a force of 3 or 4 over the sea,it will produce infrasonic waves of several decibels.Only typhoons can produce infrasonic waves of over 100 decibels.At present,scientists can only produce infrasonic weapons in the lab with the help of advanced scientific tools and powerful electric power.An ultrasonic sound______.A:is very loudB:does harm to people's healthC:cannot be heard by peopleD:is produced by the hero in movies

4.Bourdon Tube is probably the most commonly used______ measuring instrument.A.the absolute pressureB.the gauge pressureC.the vacuum pressureD.the differential pressure

更多“单选题Decibel is______.A the unit for measuring the intensity of soundB the pressure of radiating wavesC the frequency of radiating wavesD the seed of sound”相关问题

  • 第1题：

    共用题干
    第二篇
    The Magic of Sound
    Music is one of the most beautiful forms of artistic expressions ever invented.In movies and plays, music has an added function:it not only moves people but also can shock people.
    Our eardrums can withstand sound within 20 to 80 decibels（分贝）.Once sound exceeds this limit , even beautiful music will become ear-splitting noise and harm health.A strong blast（响声）of high sound can twist and break a solid iron sheet.High sound of 150 decibels can kill a healthy rat.
    In movies,sometimes the hero can produce a sound that ordinary people can't hear and only those who
    have the same ability can feel.In nature,there is actually sound that is beyond our hearing.In physics,the sound that exceeds 20,000Hz is called ultrasonic（超音波的）.Dolphins, whales and bats can make such high-frequency sound.It does no harm to health.
    Sound less than 20Hz is called infrasonic（次声）waves.When we move, the air will vibrate.The vibration of air can produce infrasonic waves.As the frequency of infrasonic waves is close to that of people's internal organs, infrasonic wave may cause resonance（共振）in human bodies.As a result,people's vision may weaken and internal organs may rupture（断裂）.However,whether an infrasonic wave can be used as a weapon depends on its intensity.If its intensity is very low,it won't damage internal organs or a person's health.If the intensity of infrasonic wave exceeds 160 decibels,it is extremely harmful.When wind blows at a force of 3 or 4 over the sea,it will produce infrasonic waves of several decibels.Only typhoons can produce infrasonic waves of over 100 decibels.At present,scientists can only produce infrasonic weapons in the lab with the help of advanced scientific tools and powerful electric power.

    It is true that the sound______.
    A:of nature is the most beautiful
    B:over 80 decibels is harmful to people
    C:of high intensity benefits animals
    D:in movies is pleasing to the ear

    答案：B
    解析：
    本篇文章主要讲了声音的奇妙之处以及超声波和次声波的一些特征。
    根据文章的标题“The Magic of Sound"以及全文可知，文章最恰当的标题为C项。其余选项表述都不全面。
    根据第二段第一、二句可知，我们的耳膜可以承受的声音在20分贝到80分贝之间，只要超过了这个界限，再美妙的音乐也会成为噪音，损害健康。由此可知，音乐也可能会对人的健康造成危害。
    根据第二段第一、二句可知，我们的耳膜可以承受的声音在20分贝到80分贝之间，超过了这个界限，再美妙的音乐也会成为噪音，损害健康。由此可见，超过80分贝的声音对人是有害的。
    第三段第二句表明，自然界中存在人类听不到的声音。根据第三段第三句可知，这种超过两万赫兹的声音在物理学中被称为超声波。由此可知，超声波是人类听不到的声音。
    根据第四段第四句可知，当次声波的频率与人体内部器官的频率相当时，就会对人体造成危害，又由常理可知振动会产生声音，可推断出人体内存在次声波，因此选择B项。只有当次声波频率与人体内部器官的频率相近时，次声波才会对人有害，所以A项错误；只有超过 160分贝的次声波才能被用作致命武器，并且由最后一段最后一句“At present, scientists can only produce infrasonic weapons in the lab…”可知，次声波用作致命武器还只是实验室的实验结果，现实中并没有出现，所以C项错误；最后一段没有表明次声波可以改善视力，所以D项错误。

  • 第2题：

    A phoneme is the smallest distinctive sound unit, incapable of change in different phonetic environments.（）

    A对

    B错


    错
    略

  • 第3题：

    Which unit is used for measuring traffic? （）

    • A、Erlang
    • B、Bit/second
    • C、Hertz
    • D、Subscribers/kHz
    • E、Subscribers/minute

    正确答案:A

  • 第4题：

    名词解释题
    撞击声压级改善量reduction of impact sound pressure level

    正确答案： 在楼板面层铺设之前和之后接收室内的平均声压级差值，以dB表示。
    解析： 暂无解析

  • 第5题：

    单选题
    What is the action that a GMDSS Radio Operator should take when a DSC distress alert is received? （）
    A

    No action is necessary，as the DSC control unit will automatically switch to the NBDP follow-on communications frequency

    B

    The operator should immediately set continuous watch on the radiotelephone frequency that is associated with the frequency band on which the distress alert was received

    C

    The Operator should immediately set continuous watch on VHF channel 70

    D

    The Operator should immediately set continuous watch on the NBDP frequency that is associated with the frequency band on which the distress alert was received


    正确答案： C
    解析： 暂无解析

  • 第6题：

    单选题
    In general, the oil mist defectors include a base plate with air blast pumpThe function of air blast pump is to （）crankcase.
    A

    supply clean air to the measuring compartment of the units for more accuracy

    B

    generaate the pressure required for the extraction of the oil mist from the

    C

    generate the pressure required for the extraction of the oil mist from the crankcase

    D

    supply clean air to the measuring track of the units for more accuracy


    正确答案： A
    解析： 暂无解析

  • 第7题：

    单选题
    Cargo handling unit is rated according to the （） to be lifted.
    A

    cargo crane

    B

    jib

    C

    safe working load

    D

    oil pressure


    正确答案： D
    解析： 暂无解析

  • 第8题：

    单选题
    A knocking sound from one cylinder of an operating air compressor indicates （）.
    A

    a defective or broken high pressure un-loader

    B

    a loose valve plate

    C

    excessive overload

    D

    no compression


    正确答案： D
    解析： 暂无解析

  • 第9题：

    单选题
    The pilot of the plane which flies faster than sound travels does not hear the thunderclaps because______.
    A

    the sound of plane engine travels slower than the plane

    B

    the frequency of the sound alters

    C

    the passage does not mention it

    D

    the pressure decreased when the plane flies in the air


    正确答案： C
    解析：
    推断题。文章第二段首句提到了题干中的话，但该段随后讲述的就是声音的产生和频率等，并没有对该问题展开论述，因此Ｃ项正确。

  • 第10题：

    单选题
    The pressure head of a water pump is given in the unit of （）.
    A

    kg

    B

    MPa

    C

    mH20

    D

    None of the above


    正确答案： D
    解析： 暂无解析

  • 第11题：

    单选题
    The pressure range between the system cut in and cut out pressures in a refrigeration unit is known as（）
    A

    opposing operational drag

    B

    pressure distribution

    C

    differential

    D

    system purge


    正确答案： D
    解析： 暂无解析

  • 第12题：

    单选题
    How can vessel personnel detect the operation of a SART in its vicinity?（）
    A

    A unique radar signal consisting of a blip code radiating outward from a SART's position along its line of bearing

    B

    A unique two tone warbling signal heard on VHF-FM ch-70

    C

    A unique two tone alarm signal heard upon the automatic unmuting of the 2182 kHz radiotelephone automatic watch receiver

    D

    The SART signal appears as a target which comes and goes; the effect of heavy swells on the SART


    正确答案： C
    解析： 暂无解析

  • 第13题：

    共用题干
    第二篇
    The Magic of Sound
    Music is one of the most beautiful forms of artistic expressions ever invented.In movies and plays, music has an added function:it not only moves people but also can shock people.
    Our eardrums can withstand sound within 20 to 80 decibels（分贝）.Once sound exceeds this limit , even beautiful music will become ear-splitting noise and harm health.A strong blast（响声）of high sound can twist and break a solid iron sheet.High sound of 150 decibels can kill a healthy rat.
    In movies,sometimes the hero can produce a sound that ordinary people can't hear and only those who
    have the same ability can feel.In nature,there is actually sound that is beyond our hearing.In physics,the sound that exceeds 20,000Hz is called ultrasonic（超音波的）.Dolphins, whales and bats can make such high-frequency sound.It does no harm to health.
    Sound less than 20Hz is called infrasonic（次声）waves.When we move, the air will vibrate.The vibration of air can produce infrasonic waves.As the frequency of infrasonic waves is close to that of people's internal organs, infrasonic wave may cause resonance（共振）in human bodies.As a result,people's vision may weaken and internal organs may rupture（断裂）.However,whether an infrasonic wave can be used as a weapon depends on its intensity.If its intensity is very low,it won't damage internal organs or a person's health.If the intensity of infrasonic wave exceeds 160 decibels,it is extremely harmful.When wind blows at a force of 3 or 4 over the sea,it will produce infrasonic waves of several decibels.Only typhoons can produce infrasonic waves of over 100 decibels.At present,scientists can only produce infrasonic weapons in the lab with the help of advanced scientific tools and powerful electric power.

    What does the author say about music?
    A:It may be harmful to people's health.
    B:It always cheers people up.
    C:It is very often difficult to understand.
    D:It sounds better when it is loud enough.

    答案：A
    解析：
    本篇文章主要讲了声音的奇妙之处以及超声波和次声波的一些特征。
    根据文章的标题“The Magic of Sound"以及全文可知，文章最恰当的标题为C项。其余选项表述都不全面。
    根据第二段第一、二句可知，我们的耳膜可以承受的声音在20分贝到80分贝之间，只要超过了这个界限，再美妙的音乐也会成为噪音，损害健康。由此可知，音乐也可能会对人的健康造成危害。
    根据第二段第一、二句可知，我们的耳膜可以承受的声音在20分贝到80分贝之间，超过了这个界限，再美妙的音乐也会成为噪音，损害健康。由此可见，超过80分贝的声音对人是有害的。
    第三段第二句表明，自然界中存在人类听不到的声音。根据第三段第三句可知，这种超过两万赫兹的声音在物理学中被称为超声波。由此可知，超声波是人类听不到的声音。
    根据第四段第四句可知，当次声波的频率与人体内部器官的频率相当时，就会对人体造成危害，又由常理可知振动会产生声音，可推断出人体内存在次声波，因此选择B项。只有当次声波频率与人体内部器官的频率相近时，次声波才会对人有害，所以A项错误；只有超过 160分贝的次声波才能被用作致命武器，并且由最后一段最后一句“At present, scientists can only produce infrasonic weapons in the lab…”可知，次声波用作致命武器还只是实验室的实验结果，现实中并没有出现，所以C项错误；最后一段没有表明次声波可以改善视力，所以D项错误。

  • 第14题：

    A phoneme is the smallest distinctive sound unit, incapable of change in different phonetic environments.（）


    正确答案:错误

  • 第15题：

    单选题
    For a continuous operation diesel engine, a duplex filter unit would be the best arrangement because （）.
    A

    changing filter elements would not interrupt engine operation

    B

    filtering occurs twice in each pass of oil through the system

    C

    clogging will not occur

    D

    dropping pressure is half of that through a single filter unit


    正确答案： C
    解析： 暂无解析

  • 第16题：

    名词解释题
    撞击声压级impact sound pressure level

    正确答案： 当测试楼板用标准撞击器激发时，在接收室内的1/3倍频程平均声压级，以dB表示。
    解析： 暂无解析

  • 第17题：

    判断题
    A phoneme is the smallest distinctive sound unit, incapable of change in different phonetic environments.（）
    A

    对

    B

    错


    正确答案： 对
    解析： 暂无解析

  • 第18题：

    单选题
    Centrifugal pumps are non-positive and a fairly （） unit.
    A

    low pressure

    B

    low discharge

    C

    low speed

    D

    high pressure


    正确答案： B
    解析： 暂无解析

  • 第19题：

    单选题
    Bourdon Tube is probably the most commonly used （） measuring instrument.
    A

    the absolute pressure

    B

    the gauge pressure

    C

    the vacuum pressure

    D

    the differential pressure


    正确答案： B
    解析： 暂无解析

  • 第20题：

    单选题
    What does a SART signal sound or look like?（）
    A

    It transmits SOS and the vessel's name and position in slow speed Morse Code

    B

    It will appear on a radar unit's PPI as a line of dots radiating outward with the innermost dot indicating the SART's position

    C

    It will appear on a radar unit's PPI as a line of dots radiating outward with the outermost dot indicating the SART's position

    D

    None of the above


    正确答案： D
    解析： 暂无解析

  • 第21题：

    单选题
    The pressure head of a pump is given in the unit of （）.
    A

    kg

    B

    MPa

    C

    meter fluid column

    D

    None of the above is true


    正确答案： C
    解析： 暂无解析

  • 第22题：

    单选题
    （） of an engine crankshaft can be detected by measuring deflections of crank webs for each unit of the engine.
    A

    Misalignment

    B

    Length

    C

    Strength

    D

    Stresses


    正确答案： D
    解析： 暂无解析

  • 第23题：

    单选题
    Which of the following can serve as the best title of this passage?
    A

    The Prefix Mach.

    B

    The Speed of Sound.

    C

    The Frequency of Sound.

    D

    The Intensity of Sound.


    正确答案： B
    解析：
    主旨题。文章首段介绍了测声速的方法，第二段就介绍了声音的产生和频率，第三段介绍了声音的强度，第四度介绍了不同介质中声速不同。综合全文，选项B“声速”概括了文章的全部内容，因此是最佳选择。其余三项只涉及文中的一部分内容，都不宜作为文章的标题。

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