大地坐标系
参考答案：
以大地经度、大地纬度和大地高来表示点的位置的坐标系。
－How long does it take us to go to your school from here?
－It takes us hour or more to go to my school by bus.
A．an; a
B．a, an
C．an, /
D．a, /
板、片状钯
