南京師范大學(xué)04年4月英語二資料7

　　「習(xí)題一」

　　1

　　What is color？ Why do some objects look red， others green，  others blue？

　　Color is caused by reflected light rays. We see color because objects reflect light. Something that is red reflects mostly red light. （It reflects a little green of blue light， too， but we do not see it.） In the same way， a green object reflects mostly green light. White objects reflect all colors of light Black objects do not reflect any light.

　　What happens to the colors of light that are not reflected？ They are absorbed by the object. The darker the color， the less light is reflected and the more light is absorbed. Light that is absorbed is turned into heat. For this reason， dark-colored clothes are warmer in the sunlight than light-colored clothes.

　　2

　　The sum spent on books and magazines seems small. Most families take at least one daily newspaper and a Sunday paper. They may take several weekly magazines， usually including the Radio Times （《無線電節(jié)目報》）。 This gives them the weekly programmers of the B.B.C. The small sum spent on books does not mean that people do very little reading. Millions of cheap， paper-backed（平裝的） books are bought every month. There are good public libraries everywhere from which books may be borrowed. Over one million books are taken out from these libraries every week-day. In some homes， however， there is less serious reading now than there was fifty years ago. Many people prefer to listen to the radio， or look at films or television. Many people seem to prefer popular picture magazines to magazines that contain serious reading.

　　3

　　Astronomers（天文學(xué)家） can tell just how hot the surface of the moon gets. The side of the moon toward the sun gets two hundred degrees hotter than boiling water. The night side reaches 243 degrees below zero.

　　In the eclipse（月食）， the earth‘s shadow fails on the moon. Then the moon’s temperature may drop 300 degrees in a very short time.

　　A temperature change like this cannot happen on the earth. Why does it happen on the moon？  Astronomers think that the surface of the moon is dust. On the earth， rocks store heat from the sun. When the sun goes down， the rocks stay warm. But the dust of the moon cannot store heat. So when the moon gets dark， the heat escapes quickly. The moon gets very cold.

　　4

　　Water is very important to living things. Without water there can be no life on Earth. All animals and plants need water. Man also needs water. We need water to drink， to cook our food and to clean ourselves. Water is needed in offices， factories and schools. Where else is water needed？

　　Water covers about seventy percent of the Earth‘s surface. There is water is seas， rivers， lakes， springs（泉） and wells.

　　Water is found almost everywhere.  Even in the driest part of the world there is some water in the air. You cannot see it or feel it when it is part of the air. The water in oceans and lakes and streams is a liquid. The water in the air is not a liquid but a gas. We call it water vapor.

　　Clouds are made of water. They may be made of tiny drops of water. They may also be made of snow crystals. Snow crystals are tiny crystals of ice. Ice is frozen water or water that has become solid.

　　「習(xí)題一答案」

　　1   顏色是什么？為什么有些東西看起來是紅色，另一些是綠色，還有些是藍(lán)色的呢？

　　顏色是由反射出的光線引起的。我們能看出顏色，是因為物體能反射光。紅色物體主要反射紅光。（它也反射一點(diǎn)綠光或藍(lán)光，但我們看不見。）同樣，綠色物體主要反射綠光。白色物體反射所有顏色的光。黑色物體不反射任何光。

　　那些沒有被反射的光的顏色怎么樣了呢？他們被物體吸收了。顏色越深，反射的光就越少，吸收的光也就越多。被吸收的光變成熱。正因如此，在陽光下，深色衣服比淺色衣服更保暖。

　　2   用于購買書籍雜志的錢看來很少，大多數(shù)家庭至少訂一份日報和一份周日版的報紙。他們也可能訂幾份周刊，通常包括《無線電節(jié)目報》。這就可以使他們知道 BBC每周的節(jié)目。在書籍上開銷少，并不是說人們不怎么看書。每月都出數(shù)以百萬計的平裝廉價書。各處都有良好的公共圖書館，可以從中借書。這些圖書館每個工作日都借出一百多萬冊書籍。然而比起五十年前，有些家庭讀書不那么認(rèn)真了。許多人情愿聽廣播或者看電影或電視。許多人似乎情愿看通俗畫報，而不看刊載嚴(yán)肅讀物的雜志。

　　3   天文學(xué)家能說出月球表面有多熱。月球面對太陽的那一面要比沸水熱200度。黑夜的那一面達(dá)到零下243度。

　　月食時，地球陰影落在月球上。月球溫度可以在短時間內(nèi)下降300度。

　　像這樣的溫度變化不可能發(fā)生在地球上。它為什么會出現(xiàn)在月球上呢？天文學(xué)家認(rèn)為，月球表面上是塵埃。在地球上，巖石貯存來自太陽的熱量。太陽落山后，巖石仍保持一定溫度。但是月球的塵埃不能貯存熱量。因此當(dāng)月球變黑以后，熱量很快消散。月球就變得非常寒冷。

　　4   水對生物來說是至關(guān)重要的。沒有水，地球上就不可能有生命。一切動植物都需要水。人也需要水。我們要喝水，用水燒飯和洗澡。機(jī)關(guān)、工廠和學(xué)校也需要水。還有別的什么地方需要水呢？

　　水約占地球表面總面積的百分之七十。海洋、河流、湖泊、泉眼和井里都有水。

　　水幾乎到處可見。即使在世界上最干旱的地方，空氣中也有水。當(dāng)水存在于空氣中時是看不見摸不著的。海洋、湖泊和溪流中的水呈液態(tài)。空氣中的水不是液態(tài)，而是氣態(tài)，我們管它叫水蒸汽。

　　云是由水形成的。它們可能是由小水滴形成的，也可能是由雪晶形成的。雪晶是細(xì)小的冰晶。冰是凍結(jié)的水或是已變成固態(tài)的水。

　　「習(xí)題二」

　　1 Finding enough meat was a problem for primitive man （原始人） . Keeping it for times when it was scarce （短缺的）was just as hard. Three ways were found to keep meat from spoiling： salting， drying and freezing.

　　People near salty waters salted their meat. At first they probably rubbed dry salt on it， but this preserved only the outside. Later they may have pickled （腌制） their meat by soaking it in salt water.

　　In hot， dry lands， men found that they could eat meat that had dried while it was still on the bones. They later learned to cut meat into strips and hang it up to dry in the hot air.

　　Men in cold climates found that frozen meat did not spoil. They could leave their meat outside and eat it when they pleased.

　　2 Strange things happen to time when you travel， because the earth is divided into twenty-four time zones （時區(qū)）， one hour apart. You can have days with more or fewer than twenty-four hours， and weeks with more or fewer than seven days.

　　If you make a five-day drip across the Atlantic Ocean（大西洋）， your ship enters a different time zone every day. As you enter each zone， the time changes one hour. Traveling west， you set your clock back； traveling east， you set it ahead. Each day of your trip has either twenty-five or twenty-three hours.

　　If you travel by ship across the Pacific（太平洋），  you cross the international date line（國際日期變更線）。 By agreement， this is the point where a new day begins. When you cross the line， you change your calendar one full day， backward or forward. Traveling east， today becomes yesterday； traveling west， it is tomorrow！

　　3 Volcanoes have been erupting（噴發(fā)） on the earth for millions of years. More than five hundreds still erupt today. These are called active volcanoes. Volcanoes are located in belts or chains. They are found where the earth‘s crust is weak. The weak spots let the hot rock escape when the volcano erupts.

　　Many volcano belts are mountain ranges along the edges of continents. One pest runs along the western coast of South American up through tire western part of the United States. Other volcanoes are found in ocean basins（盆地）。

　　About three-fifths of all active volcanoes in the world are in the Pacific Ocean（太平洋）。 Many of these volcanoes erupt under the water. The Hawaiian Island（夏威夷群島） were built by volcanoes that began erupting under water and