航海英語天文航海單項選擇題每日一練(2019.01.15)

來源：考試資料網(wǎng)

1 As observed from the Earth，the angle between lines from the Earth to the Sun and the Earth to an inferior planet is known as（）.

2 The approximate positions of the stars are based on sidereal time，which is based upon rotation of the Earth relative to（）.

3 Elongation becomes zero at（）.

4 A semidiameter correction is applied to observations of（）.

5 A variable star is one that（）.