Mercury’s（ ）is so much greater than the Earth’s that it completes more than four revolutions around the Sun in the time it takes the Earth to complete one.

Text 2 To understand how astrology works, we should first take a quick look at the sky. Although the stars are at enormous distances, they do indeed give the impression of being affixed to the inner surface of a great hollow sphere surrounding the earth. Ancient people, in fact, literally believed in the existence of such a celestial sphere. As the earth spins on its axis, the celestial sphere appears to turn about us each day, pivoting at points on a line with the earth's axis of rotation. This daily turning of the sphere carries the stars around the sky, causing most of them to rise and set, but they, and constellations they define, maintains fixed patterns on the sphere, just as the continent of Australian maintains its shape on a spinning globe of the earth. Thus the stars were called fixed stars.

The motion of the sun along the ecliptic is, of course, merely a reflection of the revolution of the earth around the sun, but the ancients believed the earth was fixed and the sun had an independent motion of its own, eastward among the stars. The glare of sunlight hides the stars in daytime, but the ancients were aware that the stars were up there even at night, and the slow eastward motion of the sun around the sky, at the rate of about thirty degrees each month, caused different stars to be visible at night at different times of the year.

The moon, revolving around the earth each month, also has an independent motion in the sky. The moon, however, changes its position relatively rapidly. Although it appears to rise and set each day, as does nearly everything else in the sky, we can see the moon changing position during as short an interval as an hour or so. The moon's path around the earth lies nearly in the same plane as the earth's path around the sun, so the moon is never seen very far from the ecliptic in the sky. There are five other objects visible to the naked eye that also appear to move in respect to the fixed background of stars on the celestial sphere. These are the planets Mercury, Venus, Mars, Jupiter, and the Saturn. All of them revolve around the sun in nearly the same plane as the earth does, so they, like the moon, always appear near the ecliptic. Because we see the planets from the moving earth, however, they behave in a complicated way, with their apparent motions on the celestial sphere reflection both their own independent motions around the sun and our motion as well.

第26题：The ancient people believed that ________.

[A] the earth was spinning on the axis of the sky

[B] the sky was a hollow sphere spinning around the earth

[C] the patterns of stars on the sky would never change

[D] the stars around the sky were not stationary

All the other five planets ________.

[A] always appear near the path of the sun

[B] are moving in a way more complicated than the earth does

[C] aren't moving around the sun as independently as the earth does

[D] are moving around the sun at the same speed as the earth does

A

When you look at the sky at night，the moon looks bigger than the stars． In fact，the moon is much smaller than the stars．It is much smaller than the earth． But the moon is much closer to us than any star． That is why it looks so big． If you hold a coin close．to your eye，it looks big．If you look at it across the room，it looks small．The moon moves around the earth． It makes one trip in about four weeks． The moon looks flat(扁的)to us． But it is a round ball，like the earth．People once thought the moon had fire(火) on it． They thought the fire made it bright．Now we know the moon is like a mirror( 镜子 )． It gets its light from the sun Our sunlight comes from the sun，too: What is the sun? The sun is star． The stars we can see have their own light． There are many big stars we can-t see． Their light has burned out． Others are still bright，but they are so far away that we can-t see them． The sun looks bigger and much brighter than other stars because it is the nearest of all stars． The sun and the other stars we see are very hot，but the air around us saves us from(使------免于) the heat(热量) of the sun．The sun gives us light and warmth．It makes plants grow and leaves turn green． It makes life possible on our earth．It is a life-giving star．

( )21． The moon looks bigger because__________ ．

A． some stars are smaller than it

B．it is between the sun and the earth

C．it is the closest to the earth

D．it is very bright

A mean sun is used as the reference for solar time for three reasons. Which reason is NOT a cause for use of a mean sun?

A.The motion of the apparent sun is along the ecliptic

B.Measurement of time is along the celestial equator

C.The speed of the Earth's revolution is not constant

D.There are variations in the Earth's rotational speed

It is stated in astrology that ________.

[A] the sun is so distant from us that it was hard to follow its motion

[B] the sun was moving westward around the sky

[C] the motion of the sun is at the rate of about thirty degrees every week

[D] the motion of the sun is similar to the revolution of the earth around the sun

A、one of the suns’ planets

B、one of the sun's planets

C、one of the sun’s planet

D、one of the suns’ planet’s

22．It takes__________ for the moon to go around the earth

A． more than a week

B． nearly a month

C． half a year

D． more than a year