单选题Only a small part of the sun’s energy reaches the earth’ s surface because most of it is ______.A absorbed by the clouds in the lower atmosphereB reflected by the gases in the upper atmosphereC lost in the upper and lower atmosphereD used to evaporate

题目
单选题
Only a small part of the sun’s energy reaches the earth’ s surface because most of it is ______.
A

absorbed by the clouds in the lower atmosphere

B

reflected by the gases in the upper atmosphere

C

lost in the upper and lower atmosphere

D

used to evaporate water from the oceans and lakes

相似考题

1.Practially every river has an upper, a middle and a lower part.事实上每条河都有上游、中游和下游。()此题为判断题(对，错)。

2.Electromagnetic EnergyWhite light seems to be a combination of all colors. The energy that comes from a source of light is not limited to the kind of energy you can see. Heat is given off by a flame or an electric light. On a cloudy day it is possible to get a sunburn even though you feel cool. Visible light and the kind of energy that produce warmth and sunburn are examples of electromagnetic energy.The sun is 93 million miles from the earth. Yet we can use energy from the sun because electromagnetic energy travels through space.Many other kinds of energy are also types of electromagnetic energy. Radio, television, and radar signals travel from transmitters to receivers as low-energy electromagnetic waves. Infrared (红外线的) radiation is an electromagnetic wave. When it is absorbed by matter, heat is produced. Waves of infrared and visible light have more energy than waves of radio, television, or radar. Ultraviolet rays (紫外线) and X-rays are electromagnetic waves with even greater amounts of energy. Infrared radiation is used in cooking food and heating buildings. Sunlight and electric lights are part of our requirements for normal living. Ultraviolet radiation is useful in killing certain disease organisms. X-rays and gamma rays have so mush energy that they travel right through solid objects. They can be used to detect and treat cancer. X-rays are used in industry to find hidden cracks in metal, and in medicine to reveal broken bones.Usually we use electricity to generate electromagnetic energy. The source of most of our energy is the sun. Heat from the sun causes water to evaporate. When the water falls to the earth as rain, some of it is trapped behind dams and then used to operate electric generators. Other generators are powered by coal, but the energy stored in coal came from the sun, too.Until recently, the source of the tremendous amount of energy given off by the sun was a puzzle. If the sun depended on chemical reactions, it would have used up all its energy long ago. Experiments with electromagnetic radiation led to the theory that mass can be converted into energy. About forty years after the theory was proposed, nuclear energy was harnessed (利用) by man. Chemical energy comes from electron (电子) rearrangement. Nuclear energy comes from a change in the nucleus of an atom. Compared with chemical reactions, nuclear reactions release millions of times more energy per pound of fuel. We now believe that the sun's energy comes from the nuclear reactions in which hydrogen is changed into helium(氦).Nuclear energy is beginning to compete with coal as an economical source of power to generate electricity. It is also being used to operate engines in large ships. Scientists continue to seek new and better methods of obtaining and using energy.A. Nuclear Reactions as the Lasting Source of the Sun's EnergyB. The Most Important Source of EnergyC. Types of Electromagnetic EnergyD. X-rays Are Used to Detect and Treat Cancer.E. Seeking New Sources of EnergyF. Nuclear Energy is Beginning to Compete with CoalParagraph 3 ______

3.Sounds which are produced with both the upper lip and the lower lip are called bilabials.()

4.In the last sentence, the word "bust" most probably means ______.A．the upper part of one's bodyB．self-portraitC．paintingD．clothes

更多“单选题Only a small part of the sun’s energy reaches the earth’ s surface because most of it is ______.A absorbed by the clouds in the lower atmosphereB reflected by the gases in the upper atmosphereC lost in the upper and lower atmosphereD used to evaporate ”相关问题

  • 第1题：

    For a purifier changing to a gravity disc with smaller hole diameter will move the interface towards the _______.

    A.bowl periphery

    B.bowl center

    C.upper surface

    D.lower surface


    正确答案：B

  • 第2题：

    In order to minimize the effects of a tender vessel，when carrying a cargo of lumber，you should ______．

    A.Maximize your deck load

    B.Distribute lumber so that those stowing most compactly per unit of weight are in the upper holds

    C.Place the heaviest woods in the lower holds

    D.Keep the vessel's frame spaces free from lumber


    正确答案：C

  • 第3题：

    共用题干
    Electromagnetic Energy
    1 White light seems to be a combination of all colors.The energy that comes from a source of light is not limited to the kind of energy you can see.Heat is given off by a flame or an electric light.On a cloudy day it is possible to get a sunburn even though you feel cool.Visible light and the kinds of energy that produce warmth and sunburn are examples of electromagnetic energy.
    2 The sun is 93 million miles from the earth.Yet we can use energy from the sun because electromagnetic energy travels through space.
    3 Many other kinds of energy are also types of electromagnetic energy.Radio,television,and radar signals travel from transmitters to receivers as low-energy electromagnetic waves.Infrared（红外线的）radiation is an electromagnetic wave.When it is absorbed by matter,heat is produced.Waves of infrared and visible light have more energy than waves of radio,television,or radar.Ultraviolet rays（紫外线）and X-rays are electromagnetic waves with even greater amounts of energy.Infrared radiation is used in cooking food and heating buildings. Sunlight and electric lights are part of our requirements for normal living.Ultraviolet radiation is useful in killing certain disease organisms.X-rays and gamma rays have so much energy that they travel through solid objects. They can be used to detect and treat cancer.X-rays are used in industry to find hidden cracks in metal,and in medicine to reveal broken bones.
    4 Usually we use electricity to generate electromagnetic energy.The source of most of our energy is the sun.Heat from the sun causes water to evaporate.When the water falls to the earth as rain,some of it is trapped behind dams and then used to operate electric generators.Other generators are powered by coal,but the energy stored in coal came from the sun,too.
    5 Until recently,the source of the tremendous amount of energy given off by the sun was a puzzle.If the sun depended on chemical reactions,it would have used up all its energy long ago.Experiments with electromagnetic radiation led to the theory that mass can be converted into energy.About forty years after the theory was proposed , nuclear energy was harnessed（利用）by man.Chemical energy comes from electron （电子）rearrangement.Nuclear energy comes from a change in the nucleus of an atom.Compared with chemical reactions,nuclear reactions release millions of times more energy per pound of fuel.We now believe that the sun's energy comes from the nuclear reactions in which hydrogen is changed into helium（氦）.
    6 Nuclear energy is beginning to compete with coal as an economical source of'power to generate electricity.It is also being used to operate engines in large ships.Scientists continue to seek new and better methods of obtaining and using energy.

    Infrared radiation can produce heat______.
    A:when it is absorbed by matter
    B:when it is cloudy
    C:because they can pass through solid objects
    D:when the sunrays are fierce.
    E:when a change in the nucleus of an atom takes place
    F:when electron rearrangement takes place

    答案：A
    解析：
    通读文章可知，第三段第一句是段落主题句，紧接着围绕第一句进行了具体阐述，根据第一句中出现的“types of electromagnetic energy”可知，第三段主要讲述几种不同种类的电磁能，应选择C项。
    根据第四段第一、二句可知，我们通常用电来生成电磁能，使用的很多能源都来自太阳。紧接着又表明，水能源于来自太阳的热能，煤储存的能量也是来自太阳。因此不难得出，第四段讲的是能量最重要的来源，即太阳。
    第五段开头提到太阳能的来源仍是个谜，随后对此进行了分析，最后得出太阳能来自核反应释放的能量。由此可知，第五段主要讲的是，氢原子转变为氦原子的核反应释放的能量是太阳能的来源。几个选项中只有A项提到核反应是太阳能的持久来源，因此选择A项。
    通读文章可知，第六段的最后一句是主题句。这句话的大意是：科学家正继续在寻找更好的新方法来获取并使用能源。几个选项中只有E项与之契合，因此选择E项。
    根据第一段第四句可知，你即便在感到凉爽的阴天，也有可能被阳光灼伤，因此选择B项。
    根据第三段第三、四句可知，红外线是电磁波，当它被物质吸收时，会产生能量。
    根据第三段倒数第二、三句可知，X射线和伽马射线之所以能用来探测和治疗癌症，是因为具有很多能量的x射线和伽马射线能穿透固体。
    根据第五段第五句可知，化学能是在电子重组时产生的。

  • 第4题：

    共用题干
    Electromagnetic Energy
    1 White light seems to be a combination of all colors.The energy that comes from a source of light is not limited to the kind of energy you can see.Heat is given off by a flame or an electric light.On a cloudy day it is possible to get a sunburn even though you feel cool.Visible light and the kinds of energy that produce warmth and sunburn are examples of electromagnetic energy.
    2 The sun is 93 million miles from the earth.Yet we can use energy from the sun because electromagnetic energy travels through space.
    3 Many other kinds of energy are also types of electromagnetic energy.Radio,television,and radar signals travel from transmitters to receivers as low-energy electromagnetic waves.Infrared（红外线的）radiation is an electromagnetic wave.When it is absorbed by matter,heat is produced.Waves of infrared and visible light have more energy than waves of radio,television,or radar.Ultraviolet rays（紫外线）and X-rays are electromagnetic waves with even greater amounts of energy.Infrared radiation is used in cooking food and heating buildings. Sunlight and electric lights are part of our requirements for normal living.Ultraviolet radiation is useful in killing certain disease organisms.X-rays and gamma rays have so much energy that they travel through solid objects. They can be used to detect and treat cancer.X-rays are used in industry to find hidden cracks in metal,and in medicine to reveal broken bones.
    4 Usually we use electricity to generate electromagnetic energy.The source of most of our energy is the sun.Heat from the sun causes water to evaporate.When the water falls to the earth as rain,some of it is trapped behind dams and then used to operate electric generators.Other generators are powered by coal,but the energy stored in coal came from the sun,too.
    5 Until recently,the source of the tremendous amount of energy given off by the sun was a puzzle.If the sun depended on chemical reactions,it would have used up all its energy long ago.Experiments with electromagnetic radiation led to the theory that mass can be converted into energy.About forty years after the theory was proposed , nuclear energy was harnessed（利用）by man.Chemical energy comes from electron （电子）rearrangement.Nuclear energy comes from a change in the nucleus of an atom.Compared with chemical reactions,nuclear reactions release millions of times more energy per pound of fuel.We now believe that the sun's energy comes from the nuclear reactions in which hydrogen is changed into helium（氦）.
    6 Nuclear energy is beginning to compete with coal as an economical source of'power to generate electricity.It is also being used to operate engines in large ships.Scientists continue to seek new and better methods of obtaining and using energy.

    Chemical energy is generated______.
    A:when it is absorbed by matter
    B:when it is cloudy
    C:because they can pass through solid objects
    D:when the sunrays are fierce.
    E:when a change in the nucleus of an atom takes place
    F:when electron rearrangement takes place

    答案：F
    解析：
    通读文章可知，第三段第一句是段落主题句，紧接着围绕第一句进行了具体阐述，根据第一句中出现的“types of electromagnetic energy”可知，第三段主要讲述几种不同种类的电磁能，应选择C项。
    根据第四段第一、二句可知，我们通常用电来生成电磁能，使用的很多能源都来自太阳。紧接着又表明，水能源于来自太阳的热能，煤储存的能量也是来自太阳。因此不难得出，第四段讲的是能量最重要的来源，即太阳。
    第五段开头提到太阳能的来源仍是个谜，随后对此进行了分析，最后得出太阳能来自核反应释放的能量。由此可知，第五段主要讲的是，氢原子转变为氦原子的核反应释放的能量是太阳能的来源。几个选项中只有A项提到核反应是太阳能的持久来源，因此选择A项。
    通读文章可知，第六段的最后一句是主题句。这句话的大意是：科学家正继续在寻找更好的新方法来获取并使用能源。几个选项中只有E项与之契合，因此选择E项。
    根据第一段第四句可知，你即便在感到凉爽的阴天，也有可能被阳光灼伤，因此选择B项。
    根据第三段第三、四句可知，红外线是电磁波，当它被物质吸收时，会产生能量。
    根据第三段倒数第二、三句可知，X射线和伽马射线之所以能用来探测和治疗癌症，是因为具有很多能量的x射线和伽马射线能穿透固体。
    根据第五段第五句可知，化学能是在电子重组时产生的。

  • 第5题：

    The deck from bow to stern is called the （）(主甲板).

    • A、main deck
    • B、tweendeck
    • C、upper deck
    • D、lower deck

    正确答案:A

  • 第6题：

    单选题
    An amplitude of the Sun in high latitudes（）.
    A

    is most accurate before sunrise

    B

    is most accurate after sunset

    C

    should only be observed when the Sun's lower limb is above the horizon

    D

    is most accurate when the Sun's center is observed on the visible horizon


    正确答案： D
    解析： 暂无解析

  • 第7题：

    单选题
    Which of the following will increase the positive stability of your vessel?（）.
    A

    Loading weight on deck

    B

    Discharging weight from lower decks

    C

    Shifting weight from upper to lower decks

    D

    Shifting weight from lower to upper decks


    正确答案： D
    解析： 暂无解析

  • 第8题：

    单选题
    The author implies that __________.
    A

    the teacher should guide all discussions by revealing her own attitude

    B

    in some aspects of social studies a greater variety of methods can be used in the upper grades than in the lower grades

    C

    people usually act on the basis of reasoning rather than emotion

    D

    children’s attitudes often come from those of other children


    正确答案： B
    解析：
    根据倒数第二段可知，通过同附近警察的教室聊天(classroom chat)可以让害怕警察的一年级学生改变他们的态度。同样地，大一点孩子可以通过讨论(discussion)、调查(research)、课外阅读(outside reading)和全天的旅行(all-day trips)来培养态度。由此可推断出与低年级学生相比，高年级学生可以使用更多的方法，故答案选B。

  • 第9题：

    单选题
    The weight of the container and its contents is supported on deck by what part(s)?（）.
    A

    Four lower corner castings

    B

    Bottom，side，and end rails

    C

    Bottom flooring，side，and end rails

    D

    Bottom flooring only


    正确答案： C
    解析： 暂无解析

  • 第10题：

    单选题
    Without the sun’s light ______ the earth’s surface, it would be so cold that life could not exist on the earth.
    A

    warms

    B

    warmed

    C

    warming

    D

    to warm


    正确答案： D
    解析：
    句意：没有阳光温暖地球表面，地球就会非常寒冷，生物就无法在地球上生存。Without加独立主格，分词的主语the sun’s light和warm之间应该是主动关系，用现在分词，故为C。

  • 第11题：

    单选题
    A pumproom is suspected of accumulating gases after a ventilation machinery breakdown. Where should the combustible gas indicator case be placed when testing the pumproom atmosphere for combustible gases?（）.
    A

    In the lower level of the pumproom

    B

    In the middle level of the pumproom

    C

    In the upper level of the pumproom

    D

    On the deck outside the pumproom


    正确答案： B
    解析： 暂无解析

  • 第12题：

    填空题
    表达式’Hello world’.lower（）.upper（）的值为（）。

    正确答案： 'HELLO WORLD'
    解析： 暂无解析

  • 第13题：

    A pumproom is suspected of accumulating gases after a ventilation machinery breakdown. Where should the combustible gas indicator case be placed when testing the pumproom atmosphere for combustible gases?

    A.In the lower level of the pumproom

    B.In the middle level of the pumproom

    C.In the upper level of the pumproom

    D.On the deck outside the pumproom


    正确答案：D

  • 第14题：

    Pedestal cranes have limit switches to restrict movement of which function（s）________．

    A.Hoist upper & lower limits

    B.Luff travel limits

    C.Rider block hoist upper & lower limits

    D.All of the above


    正确答案：D

  • 第15题：

    共用题干
    Electromagnetic Energy
    1 White light seems to be a combination of all colors.The energy that comes from a source of light is not limited to the kind of energy you can see.Heat is given off by a flame or an electric light.On a cloudy day it is possible to get a sunburn even though you feel cool.Visible light and the kinds of energy that produce warmth and sunburn are examples of electromagnetic energy.
    2 The sun is 93 million miles from the earth.Yet we can use energy from the sun because electromagnetic energy travels through space.
    3 Many other kinds of energy are also types of electromagnetic energy.Radio,television,and radar signals travel from transmitters to receivers as low-energy electromagnetic waves.Infrared（红外线的）radiation is an electromagnetic wave.When it is absorbed by matter,heat is produced.Waves of infrared and visible light have more energy than waves of radio,television,or radar.Ultraviolet rays（紫外线）and X-rays are electromagnetic waves with even greater amounts of energy.Infrared radiation is used in cooking food and heating buildings. Sunlight and electric lights are part of our requirements for normal living.Ultraviolet radiation is useful in killing certain disease organisms.X-rays and gamma rays have so much energy that they travel through solid objects. They can be used to detect and treat cancer.X-rays are used in industry to find hidden cracks in metal,and in medicine to reveal broken bones.
    4 Usually we use electricity to generate electromagnetic energy.The source of most of our energy is the sun.Heat from the sun causes water to evaporate.When the water falls to the earth as rain,some of it is trapped behind dams and then used to operate electric generators.Other generators are powered by coal,but the energy stored in coal came from the sun,too.
    5 Until recently,the source of the tremendous amount of energy given off by the sun was a puzzle.If the sun depended on chemical reactions,it would have used up all its energy long ago.Experiments with electromagnetic radiation led to the theory that mass can be converted into energy.About forty years after the theory was proposed , nuclear energy was harnessed（利用）by man.Chemical energy comes from electron （电子）rearrangement.Nuclear energy comes from a change in the nucleus of an atom.Compared with chemical reactions,nuclear reactions release millions of times more energy per pound of fuel.We now believe that the sun's energy comes from the nuclear reactions in which hydrogen is changed into helium（氦）.
    6 Nuclear energy is beginning to compete with coal as an economical source of'power to generate electricity.It is also being used to operate engines in large ships.Scientists continue to seek new and better methods of obtaining and using energy.

    Paragraph 4______
    A:Nuclear Reactions as the Lasting Source of the Sun's Energy
    B:The Most Important Source of Energy
    C:Types of Electromagnetic Energy
    D:The Machines Used for Energy Generation
    E:Seeking New Sources of Energy
    F:The Use of Ultravio1et Radiation in Medicine

    答案：B
    解析：
    通读文章可知，第三段第一句是段落主题句，紧接着围绕第一句进行了具体阐述，根据第一句中出现的“types of electromagnetic energy”可知，第三段主要讲述几种不同种类的电磁能，应选择C项。
    根据第四段第一、二句可知，我们通常用电来生成电磁能，使用的很多能源都来自太阳。紧接着又表明，水能源于来自太阳的热能，煤储存的能量也是来自太阳。因此不难得出，第四段讲的是能量最重要的来源，即太阳。
    第五段开头提到太阳能的来源仍是个谜，随后对此进行了分析，最后得出太阳能来自核反应释放的能量。由此可知，第五段主要讲的是，氢原子转变为氦原子的核反应释放的能量是太阳能的来源。几个选项中只有A项提到核反应是太阳能的持久来源，因此选择A项。
    通读文章可知，第六段的最后一句是主题句。这句话的大意是：科学家正继续在寻找更好的新方法来获取并使用能源。几个选项中只有E项与之契合，因此选择E项。
    根据第一段第四句可知，你即便在感到凉爽的阴天，也有可能被阳光灼伤，因此选择B项。
    根据第三段第三、四句可知，红外线是电磁波，当它被物质吸收时，会产生能量。
    根据第三段倒数第二、三句可知，X射线和伽马射线之所以能用来探测和治疗癌症，是因为具有很多能量的x射线和伽马射线能穿透固体。
    根据第五段第五句可知，化学能是在电子重组时产生的。

  • 第16题：

    共用题干
    Electromagnetic Energy

    1 White light seems to be a combination of all colors.The energy that comes from a source of light is
    not limited to the kind of energy you can see.Heat is given off by a flame or an electric light.On a cloudy
    day it is possible to get a sunburn even though you feel cool.Visible light and the kind of energy that produce
    warmth and sunburn are examples of electromagnetic energy.
    2 The sun is 93 million miles away from the earth.Yct we can use energy from die sun because elec-
    tromagnetic energy travels through space.
    3 Many other kinds of energy are also types of electromagnetic energy.Radio,television,and radar signais
    travel from transmitters to receivers as low-energy electromagnetic waves. Infrared（红外线的）radiation is an
    electromagnetic wave.When it is absorbed by matter,heat is produced.Wayes of infrared and visible light
    have more energy than waves of radio,television,or radar. Ultraviolet rays（紫外线）and X-rays are eleetro-
    magnetic waves with even greater amounts of energy.Infrared radiation is used in cooking food and heating
    buildings.Sunlight and electric lights are part of our requirements for normal living. Ultraviolet radiation is
    useful in killing certain disease organisms.X-rays and gamma rays have so much energy that they travel right
    through solid objects.They can be used to detect and treat cancer。 X-rays are used in industry to find hidden
    cracks in metal,and in medicine to reveal broken bones.
    4 Usually we use electricity to generate electromagnetic energy.The source of most of our energy is the
    sun.Heat from the sun causes water to evaporate.When the water falls to the earth as rain,some of it is
    trapped behind dams and then used to operate electric generators,Other generators are powered by coal,but
    the energy stored in coal came from the sun,too.
    5 Until recently,the source of the tremendous amount of energy given off by the sun was a puzzle.If
    the sun depended on chemical reactions,it would have used up all its energy long ago.Experiments with
    electromagnetic radiation led to the theory that mass can be converted into energy．入bout forty years after the
    theory was proposed , nuclear energy was harnessed（利用）by man. Chemical energy comes from electron
    （电子）rearrangement. Nuclear energy comes from a change in the nucleus of an atom. Compared with chemi-
    cal reactions,nuclear reactions release millions of times more energy per pound of fuel.We now believe that
    the sun's energy comes from the nuclear reactions in which hydrogen is changed into helium（氦）.
    6 Nuclear energy is beginning to compete with coal as an economical source of power to generate elec-
    tricity.It is also being used to operate engines in large ships.Scientists continue to seek new and better
    methods of obtaining and using energy.

    Paragraph 4__________________
    A:Nuclear Reactions as the Lasting Source of the Sun's Energy
    B:The Most Imoprtant Source of Energy
    C:Types of Eleetromagnetie Energy
    D:X-rays Are Used to Detect and Treat Cancer
    E:Seeking New Sourees of Energy
    F:Nuclear Energy Is Beginning to Compete With Coal

    答案：B
    解析：
    第三段的第一句为主题句，意为：许多其他种类的能量也是不同类型的电磁能。该段 列举了电磁能的具体例子，C项“Types of Electromagnetic Energy（电磁能的类型）”与主题句意 思吻合，故选C。
    第四段的第二句为主题句，意为：我们的能量大多来白太阳。B项“The Most Important Source of Energy（最重要的能量来源）”与主题句意思吻合，故选B。
    第五段的最后一句为主题句，意为；我们现在相信太阳的能量来自核反应，在此过程 中，氢转变为氦。A项“Nuclear Reactions as the Lasting Source of the Sun' s Energy（核反应是太 阳能最持久的来源）”与主题句意思吻合，故选A。
    第六段的最后一句为主题句，意为：科学家仍在继续寻找获取和使用能量的新的、更好 的方法。E项“Seeking New Sources of Energy（寻找新的能源）”与主题句意思吻合，故选E。
    第一段的最后一句指出，“可见光和其他能产生热量和造成晒伤的能量都是电磁能的 例子”。故选A。
    第二段的第二句指出，“我们能使用太阳能，因为电磁能可以在太空中穿梭”。故选B。
    第四段的最后一句指出，“其他的发电机靠煤炭驱动，但是，煤炭中储存的能量也来自 于太阳”。C项中的“came from the sun (来自太阳）”与原句意思相符，故选C。
    第五段的第五句指出，化学能来自于电子重组。故选F。第4部分：阅读理解第一篇 本文介绍了引起食物中毒的原因及食物中毒的预防和治疗处理措施。

  • 第17题：

    上甲板（）

    • A、lower deck
    • B、upper deck
    • C、main deck
    • D、bridge deck

    正确答案:B

  • 第18题：

    单选题
    The atmosphere in a tank is too lean if it is（）.
    A

    incapable of supporting combustion because the hydrocarbon content is below the LFL (Lower Flammable Limit)

    B

    capable of supporting combustion because the hydrocarbon content is above the UFL (Upper Flammable Limit)

    C

    capable of supporting a fire once started

    D

    not safe for ballasting


    正确答案： B
    解析： 暂无解析

  • 第19题：

    单选题
    In order to minimize the effects of a tender vessel，when carrying a cargo of lumber，you should（）.
    A

    maximize your deck load

    B

    distribute lumber so that those stowing most compactly per unit of weight are in the upper holds

    C

    place the heaviest woods in the lower holds

    D

    keep the vessel's frame spaces free from lumber


    正确答案： B
    解析： 暂无解析

  • 第20题：

    单选题
    A centrifuge of which the bowl is arranged as the upper and lower parts separate discharges the sludge（）
    A

    by opening the separator manually

    B

    by separating the lower part from the upper part automatically

    C

    by separating the upper part from the lower part automatically

    D

    continuously


    正确答案： C
    解析： 暂无解析

  • 第21题：

    单选题
    We learn from the passage that ______.
    A

    all living things on the earth depend on the sun for their food

    B

    a forest looks dark in winter because it absorbs solar energy

    C

    only 0.023 of the energy from the sun is made use of on the earth

    D

    greenhouse gases allow heat energy to escape from the earth’ s surface


    正确答案： A
    解析：
    根据第一段Sunlight also provides the energy used by green plants to make their own food，阳光给绿色植物提供能量使其生产自己的食物，故选A。

  • 第22题：

    单选题
    Which of the following will increase the height of the center of buoyancy for your vessel?（）.
    A

    Discharging weight from lower decks

    B

    Loading weight in upper decks

    C

    Shifting weight from lower to upper decks

    D

    Shifting weight from upper to lower decks


    正确答案： C
    解析： 暂无解析

  • 第23题：

    单选题
    Pedestal cranes have limit switches to restrict movement of which function（s）（）.
    A

    Hoist upper & lower limits

    B

    Luff travel limits

    C

    Rider block hoist upper & lower limits

    D

    All of the above


    正确答案： C
    解析： 暂无解析

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