Water is very important to living things. Without water there can be no life on the 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. Water is needed everywhere.
There is water in seas, rivers and lakes. Water is found almost everywhere. Even in the driest part of the world, there is some water in the air. You cannot see or feel it when it is a part of the air. The water in the seas, rivers and lakes is a liquid. The water in the air is a gas, and we call it water vapor(水蒸气).
Clouds are made of water. They may be made of very small drops of water. They may also be made of snow crystals(晶体). Snow crystals are very, very small crystals of ice. Ice is frozen water. It is a solid(固体). There can be snow and ice everywhere in winter.
Water may be a solid or liquid (液体) or a gas. When it is a solid, it may be as hard as a stone. When it is a liquid, you can drink it. When it is a gas, you can not see or feel it.
Choose the best answer
【小题1】Where can we find water?| A．We can find water when it turns into vapor. |
| B．Water can be found almost everywhere. |
| C．We can see it in deserts(沙漠) here and there. |
| D．Water is only in seas and rivers. |
| A．when it is a liquid | B．when it is a solid |
| C．When it is in the air | D．When it is turned into ice |
| A．seas, rivers and lakes |
| B．a big piece of ice |
| C．very small drops of water or snow crystals |
| D．water in its solid state |
| A．ice, snow and air | B．solid, gas and vapor |
| C．drops of water, ice and snow | D．solid, liquid and gas |
| A．crops need water | B．all living things need water |
| C．all animals need water | D．all plants need water |
Some scientists believe that birds do sing some of the time just because they are happy. However, they sing most of the time for a very different reason. Their singing is actually a warning to other birds to stay out of their territory.
Do you know what a “territory” is? A territory is an area that an animal, usually the male, claims (声称) as its own. Only he and his family are welcome there. No other families of the same species are welcome. Your house is your territory where only your family and friends are welcome.If a stranger should enter your territory and threaten you, you
might shout. Probably this would be enough to frighten him away.
If so, you have actually frightened the stranger away without having to fight him. A bird does the same thing. But he expects an outsider almost any time, especially at nesting (筑巢) season. So he is screaming all the time, whether he can see an outsider or not. This screaming is what we call a bird’s song, and it is usually enough to keep an outsider away.
【小题1】Some scientists believe that most of the time bird’s singing is actually _______.
| A．an expression of happiness | B．a way of warning |
| C．an expression of anger | D．a way of greeting |
| A．A place where families of other species are not accepted. |
| B．A place where a bird may shout at the top of its voice. |
| C．An area for which birds fight against each other. |
| D．An area which a bird considers to be its own. |
| A．Because they want to invite more friends. |
| B．Because their singing helps frighten outsiders away. |
| C．Because they want to find outsiders around. |
| D．Because their singing helps get rid of their fears. |
| A．By comparing birds with human beings. | B．By reporting experiment results. |
| C．By describing birds’ daily life. | D．By telling a bird’s story. |
Natural Disasters
Earthquakes are natural disasters. They are the shaking of the earth’s surface（表面）. The earth makes these natural earthquakes in order to release pressure（释放压力）.
More than a million earthquakes happen in the world each year. Earthquakes usually last less than a minute but you can feel them. The scary thing about earthquakes is that they begin with no warning. But scientists are still working on the problem.
There are about 20 plates（板块）along the surface of the earth that move slowly all the time next to each other. When the plates touch each other, huge rocks are created（创造）and explode（爆炸）with great power（力量）, causing an earthquake. As the plates move, they put pressure on themselves and each other. When the pressure is large enough, the crust（地壳）is forced（被迫）to break.
Shaking and ground breaking are the main effects（影响）created by earthquakes. After an earthquake is over, buildings are usually damaged（破坏）and people get hurt even killed.
Some people think animals can predict（预言）an earthquake. The earliest reference（参考） about unusual animal behavior is from Greece in 373 BC. Rats and snakes reportedly left their homes and headed for safety several days before an earthquake. Scientists can easily explain the cause of unusual animal behavior seconds before humans feel an earthquake. Very few humans notice the smaller P wave that travels the fastest from the earthquake source（源）and arrives before the larger S wave. But many animals are able to feel the P wave seconds before the S wave arrives. As for sensing an earthquake days or weeks before it happens, that’s a different story. Scientists have tried many different ways of predicting earthquakes, but none have been successful. They need to do much research on this subject.
So what should you do when an earthquake begins? If you are inside a building, you should take cover under a table. If you are outside, you should stay out in an open place.
【小题1】An earthquake happens because ________.| A．the earth wants to release pressure |
| B．there are more creatures on the earth |
| C．there are about 30 plates along the surface of the earth |
| D．people damaged the surface of the earth |
| A．The places of earthquakes. | B．The reasons for earthquakes. |
| C．The ways of predicting earthquakes. | D．The bad result of an earthquake. |
| A．are very clever | B．can create an earthquake |
| C．like living in new places with their friends | D．can feel the P wave seconds before the S wave arrives |
| A．we should protect the animals before earthquakes |
| B．scientists can know earthquakes before they happen |
| C．people should learn to keep safe during earthquakes |
| D．earthquakes are the most dangerous natural disasters |
What will the houses of the future look like? Could it have gardens on its walls, or a pool with fish for dinner? Architects（建筑师）believe that they are all possibilities. The only thing for sure is that the houses will be as green as possible.
| The tree house Many architects in the world would like to build a “tree house”. Like a leaf, the surface of the house collects sunlight during the day. The energy can be used to heat water, produce electricity, and even create fresh air for the home. The “root” of the house is deep under the ground. It uses the soil to control the home’s temperature. |
| The lizard house Like a lizard（蜥蜴）, changing colours with the weather is the most important design of a lizard house. When it’s in the bright sun, the cover of the house will turn dark to protect it from strong heat. During dark days, it turns white and takes in as much light and heat as possible to produce energy. |
| Meals at home This design is perhaps as much about the future of food production as architecture（建筑风格）. It has gardens on the outside wall of the house. People can plant tomatoes, carrots and green tea in them. So every day in the morning, you just need to walk outside and collect your meals. |
| Learning from the past Looking to the future isn’t the only way to be green. Sometimes, ancient techniques（技术）can also help cut down energy use. For example, a chimney can be a useful air conditioner because it is easier for hot air to flow out of the chimney. |
| A．the root of a leaf | B．the energy from sunlight |
| C．the soil under the ground | D．the tree planted at home |
| A．It will turn white. | B．It will produce energy. |
| C．It will produce light. | D．It will turn dark. |
| A．be more delicious | B．need more cooks |
| C．be greener | D．be easy to cook |
| A．Green houses of the future. | B．Different kinds of houses. |
| C．The greener, the better. | D．How to build green house. |
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