航海英語(yǔ)天文航海單項(xiàng)選擇題每日一練(2019.01.20)

來(lái)源：考試資料網(wǎng)

1 Perihelion is the point where the Sun（）.

2 A marine sextant has the index arm set at zero and the reflected image of the horizon forms a continuous line with the actual image. When the sextant is rotated about the line of sight the images separate. The sextant has（）.

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3 A first magnitude star is（）.

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4 After Venus passes the point of greatest elongation east in its orbit，the first position in which the elongation will be zero is（）.

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5 A sidereal day is shorter than a solar day. This difference is due to（）.

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