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单选题
On navigational aids，what does the light characteristic Fl(2+1) mean?（）
A
A flashing light combined with a fixed light of greater brightness
B
Light flashes combined in groups，with a different number of flashes in each group
C
A light showing groups of two or more flashes at regular intervals
D
A fixed light varied at regular intervals by groups of two or more flashes of greater brightness
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更多 “单选题On navigational aids，what does the light characteristic Fl(2+1) mean?（）A A flashing light combined with a fixed light of greater brightnessB Light flashes combined in groups，with a different number of flashes in each groupC A light showing groups of two or more flashes at regular intervalsD A fixed light varied at regular intervals by groups of two or more flashes of greater brightness” 相关考题
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() the passage, what does the author really want to inform. us?
A、according toB、due toC、Based toD、In light of
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Which is a weekly publication advising mariners of important matters affecting navigational safety?A.Light ListB.Notice to MarinersC.Coast PilotD.Sailing Directions
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The symbol which appears beside a light on a chart reads Gp Fl R (2) 10 sec 160 ft 19M. Which characteristic describes the light?A.It is visible 10 milesB.Its distinguishing number is 19MC.It has a radar reflectorD.None of the above
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The charts show two dashed lines crossing the river justsouth of St. Catherine Bar Light. What does this indicate?A.Overhead power linesB.Louisiana-Mississippi ferry crossingsC.Two railroad trestlesD.Two submerged oil pipelines
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The operation of which aids to navigation may be suspended during war or national emergency ________．A.Navigational satellitesB.LoranC.OmegaD.Any of the above
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A buoy marking a wreck will show a(an) ______.A.white light FL (2) and a topmark of 2 black spheresB.occulting green light and may be letteredC.yellow light and will be numberedD.continuous quick white light and may be numbered
考题
If several fixed navigational lights are visible at the same time, each one may be positively identified by checking all of the following EXCEPT what against the Light List?______.A.RhythmB.PeriodC.IntensityD.Color
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共用题干
Learn about Light1 .Ancient civilizations were amazed by the existence of light for thousands of years. The Greek philosophers believed that light was made up of countless,tiny particles that enter the human eye and create what we call vision. However,Empedocles and a Dutch scientist named Christian Huygens believed that light was like a wave. According to them,light spread out and travelled like a straight line. This theory was accepted during the 19th century.2 .In 1905,Albert Einstein published a research paper in which he explained what is re-ferred to as the photoelectric effect. This theory explains that particles make up light.The particles Einstein was referring to are weightless bundles（束）of electromagnetic（电磁）energy called photons（光子）.Today,scientists agree that light has a dual（二重）nature一it is part particle and part wave. It is a form of energy that allows us to see things around us.3 .Things that give off light are known as sources of light. During the day,the primary source of light is the sun. Other sources of light include stars,flames,flashlights,street lamps and glowing gases in glass tube.4 .When we draw the way light travels we always use straight lines. This is because nor-mally light rays travel in a straight line. However,there are some instances that can change the path and even the nature of light. They are reflection,absorption,interference（干扰）, etc.5 .Physicists have attempted to measure the speed of light since the early times. In 1849, Hippolyte Fizeau conducted an experiment by directing a beam of light to a mirror located kilometers away and placed a rotating cogwheel（旋转齿轮）between the beam and the mirror. From the rate of rotation of the wheel,number of wheel's teeth and distance of the mirror,he was able to calculate that the speed of light is 313 million meters per second. In a vacuum（真空）,however,the speed of light is 299,792,458 meters per second. This is about a million times faster than the speed of an airplane.Paragraph 2______A: How Is the Nature of Light Explained Today?B: What Are Sources of Light?C: How Did Physicists Measure the Speed of Light?D: How Does Light Travel?E: How Did People Think of Light Years Ago?F: What Causes a Shadow?
考题
What physical characteristic does a retinal scan biometric device measure?视网膜扫描设备检测哪些人体物理特性？（）A、The pattern of light receptors at the back of the eye眼底光受体组织的图案B、The pattern of blood vessels at the back of the eye眼底血管的图案C、The amount of light reaching the retina视网膜受光量
考题
单选题A preferred-channel buoy will show a（）.A
white light whose characteristic is Morse (A)B
group-occulting white lightC
composite group-flashing (2 + 1) white lightD
composite group-flashing (2 + 1) red or green light
考题
单选题Aids to navigation marking the intracoastal waterway can be identified by（）.A
the letters ICW after the aid's number or letterB
yellow stripes，squares，or triangles marked on themC
white retroreflective materialD
the light characteristic and color for lighted aids
考题
单选题What physical characteristic does a retinal scan biometric device measure?视网膜扫描设备检测哪些人体物理特性？（）A
The pattern of light receptors at the back of the eye眼底光受体组织的图案B
The pattern of blood vessels at the back of the eye眼底血管的图案C
The amount of light reaching the retina视网膜受光量
考题
单选题There are many navigational aids（）.A
in chief engineer's roomB
in chief officer's roomC
on the bridgeD
on deck
考题
单选题A buoy having red and green horizontal bands would have a light characteristic of（）.A
group occultingB
composite group flashingC
Morse letter AD
quick flashing
考题
单选题What is the light characteristic of a lighted，preferred-channel buoy? （）A
Group flashingB
Composite group flashingC
Interrupted quick flashingD
Fixed and flashing
考题
单选题A buoy marking a wreck will show a(n)（）.A
white light FL (2) and a topmark of 2 black spheresB
occulting green light and may be letteredC
yellow light and will be numberedD
continuous quick white light and may be numbered
考题
单选题What is the primary purpose for Digital Selective Calling (DSC)?（）A
DSC provides reception of weather and navigational warnings plus search and rescue informationB
DSC provides low-cost，routine communications for the vessel operatorC
DSC is to be used for transmitting and receiving distress alerts to and from other ships or coast radio stations via radioD
This aids SAR authorities in tracking a vessel's position by satellite
考题
单选题You are underway and pass by a lighthouse. Its light，which was white since you first sighted it，changes to red. This means（）.A
the light is characterized as alternately flashingB
the lighthouse has lost power and has switched to emergency lightingC
it is the identifying light characteristic of the lighthouseD
you have entered an area of shoal water or other hazard
考题
单选题If several fixed navigational lights are visible at the same time，each one may be positively identified by checking all of the following EXCEPT what against the Light List?（）A
RhythmB
PeriodC
IntensityD
Color
考题
单选题Which of the following shall not the officers in charge of the navigational watch do?（）A
continue to be responsible for the safe navigation of the shipB
Leave the bridgeC
Keep the watch on the bridgeD
Use any available navigational aids necessary to ensure that the ship follows the planned course
考题
单选题The charts show two dashed lines crossing the river justsouth of St. Catherine Bar Light. What does this indicate? （）A
Overhead power linesB
Louisiana-Mississippi ferry crossingsC
Two railroad trestlesD
Two submerged oil pipelines
考题
单选题A light characteristic of composite group flashing indicates that there is a(n)（）.A
sharp turn in the channelB
narrowing in the channel at that pointC
junction in the channelD
obstruction that must be left to port
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