单项选择题
In the navigational triangle，the angle at the elevated pole is the（）.
A.meridian angle B.altitude C.right ascension D.azimuth angle
单项选择题 In the horizon system of coordinates what is equivalent to latitude on the Earth?（）.
单项选择题 In the horizon system of coordinates what is equivalent to the equator on the Earth?（）.
单项选择题 In order for a star to be used for a sight at lower transit，the star must（）.
