單項選擇題Mars will not be visible（）.

A.at elongation angles near 180°
B.from quadrature to opposition
C.at conjunction
D.at opposition


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1.單項選擇題It is difficult to determine which limb of the Moon is fully illuminated（）.

A.when the Moon is low in the sky at rising or setting
B.at the new Moon phase
C.when taking Moon sights during daylight
D.when the terminator is nearly vertical

2.單項選擇題In working out a local apparent noon sight for your latitude，you subtract the Ho from 90°. The 90°represents the angular distance from（）.

A.the equator to the elevated pole
B.your horizon to your zenith
C.your zenith to the elevated pole
D.the geographical position of the Sun to the elevated pole

3.單項選擇題In the navigational triangle，the angle at the elevated pole is the（）.

A.meridian angle
B.altitude
C.right ascension
D.azimuth angle

4.單項選擇題In the horizon system of coordinates what is equivalent to latitude on the Earth?（）.

A.Altitude
B.Zenith
C.Declination
D.Zenith distance

5.單項選擇題In the horizon system of coordinates what is equivalent to the equator on the Earth?（）.

A.Prime vertical circle
B.Principal vertical circle
C.Parallels of altitude
D.Horizon