第33题:[单选题] The equator is ______. A.the great circle of the Earth perpendicular to the axis B.the line to which all celestial observations are reduced C.the line from which a celestial body's altitude is measured D.All of the above 参考答案:A 【参考译文】赤道是垂直于地轴的大圆。 【解 析】equator赤道 perpendicular to垂直于