单项选择题
The height of eye correction is smaller than geometrical dip because of （）.
A. the angle between the horizontal and the line of sight to the visible horizon B. index error C. parallax D. terrestrial refraction
单项选择题 The height of a light is measured from which reference plane?（）
单项选择题 The Earth’s irregular heating is caused by （）.
单项选择题 The Earth has the shape of a(n) （）.
