单项选择题
The approximate positions of the stars are based on sidereal time，which is based upon rotation of the Earth relative to（）.
A.winter solstice
B.autumnal equinox
C.summer solstice
D.vernal equinox
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相关考题
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单项选择题
The angle measured at the observer’s meridian from the elevated pole，clockwise or counterclockwise up to 180°，to the vertical circle of the body is the（）.
A.local hour angle
B.azimuth angle
C.meridian angle
D.longitude -
单项选择题
The angle at the pole measured through 180°from the prime meridian to the meridian of a point is known as（）.
A.the departure
B.the polar arc
C.longitude
D.Greenwich hour angle -
单项选择题
The altitude at LAN may be observed by starting several minutes in advance and continuing until a maximum altitude occurs. This procedure should not be used（）.
A.when the declination and latitude are of different names
B.when the declination is greater than and the same name as the latitude
C.if the vessel is stopped or making bare steerageway
D.on a fast vessel on northerly or southerly headings
