单项选择题
In order for a star to be used for a sight at lower transit，the star must（）.
A.be circumpolar B.have a declination equal to or greater than your latitude C.have a GHA of 180° D.have the SHA equal to or less than the LHA
单项选择题 In low latitudes，a first quarter Moon will always rise at about（）.
单项选择题 In general，the most effective period for observing stars and planets occurs during the darker limit of（）.
单项选择题 Elongation becomes zero at（）.
