Phrases and Expressions
1.a great many 很多
2.above all 首先，首要
3.as a rule 通常;一般说来
together with 和
First of all let us consider the earth (that is to say， the world) as a planet revolving round the sun.The earth is one of nine planets which move in orbit round the sun.These nine planets， together with the sun， make up what is called our solar systems.How this wonderful system started and what kept it working with such wonderful accuracy is largely a mystery but astronomers tell us that it is only one of millions of similar systems in space， and one of the smallest.
The stars which we see glittering in the sky on a dark and cloudless night are almost certainly the suns of other solar systems more of less like our own， but they are so far away in space that it is unlikely that we shall ever get to know very much about them.About our own solar system， however， we are learning more every day.
Before the American and Russian astronauts made their thrilling journeys into outer space it was difficult for us to realize what our earth looked like from hundreds of thousands of miles away， but the photographs which the astronauts were able to take show us the earth in space looking not very different from what the moon looks like when we look at it from the earth.The earth is， however， very different from the moon， which the American astronauts have found to be without life or vegetation， whereas our earth is very much alive in every respect.The moon， by the way， is called a satellite because it goes round our earth as well as round the sun.In our words， it goes round the sun with our earth.
The surface of our earth is covered by masses of land and larger areas of water.Let us consider the water areas first.The total water area is about three times as large as the land area.The very large separate areas of water are called “oceans” and the lesser areas are called “seas.”
In most of the oceans and seas some of the water is found to be flowing in a particular direction ―that is to say， from one part towards another part of the ocean or sea concerned.The water which is flowing in this manner is said to be moving as a “current.” There are many thousands of currents in the waters of the oceans and seas， but only certain of the stronger and better marked currents are specially named and of great importance.There currents are important because they affect the climate of the land areas close to where they flow and also because they carry large quantities of microscopic animal and vegetable life which forms a large part of the food for fishes.
The nature and characteristics of the surface of the land areas of the earth vary a great deal from area to area and from place to place.The surface of some areas consists largely of high mountains and deep valleys whilst， in other areas， most of the surface consists of plains.If one made a journey over the Continents one world find every kind of surface including mountain ranges， plains， plateaux， deserts， tropical forestlands and empty areas covered permanently by ice and snow.
When thinking and learning about the world we should not forget that our world is the home of a vary great many different people ― peoples with different coloured skins， living very different lives and having very different ideas about a great many important things such as religion， government， education and social behaviour.The circumstances under which different people live make a great difference between the way in which they live and the way in which we live， and it ought to be our business to try to understand those different circumstances so that we can better understand people of other lands.Above all， we should avoid deciding what we think about people different from ourselves without first having learned a great deal about them and the kind of lives they have to live.It is true to say that the more we learn about other people ， the better we understand their ideas and， as a rule， the better we like those people themselves.