The rockets take astronauts and man-made satellites into space. The satellites are used for communication, weather monitoring and research. But how do satellites stay up without falling down?
There are two opposite forces (力量) acting on the satellite. One of them is the force of gravitation (地心引力), which tries to pull the satellite towards the earth. The other force is created by the rotation (旋轉(zhuǎn)) of the satellite around the earth. This force tries to take the satellite away from the earth. With these two forces, the satellite goes round and round. The gravitational pull of the earth (the force which pulls everything towards the ground) is like a rope which keeps the satellite from flying away.
Everything that goes up has to come down. It is only a matter of time before a satellite comes back to the earth. As time goes by, the satellite loses its speed, which makes the gravitational pull stronger than the force pulling it away. This makes the satellite crash (墜落) down to the earth.
小題1:Which of the following uses of satellites is NOT mentioned?
A．communication
B．monitoring the weather condition
C．doing some research
D．taking pictures
小題2:The force that pulls the satellite towards the earth is created by ________.
A．the earth
B．the satellite itself
C．the rotation of the satellite
D．the rope
小題3:Why can’t the satellites fly away?
A．Because of the force from the earth.
B．Because the satellite is too big.
C．Because of the force created by the rotation of the satellite around the earth.
D．Because people on earth have made ropes to tie the satellites tightly.
小題4:The satellite will finally crashes down to the earth ________.
A．when it flies faster
B．when its speed slows down
C．when people cut the rope
D．when there is no electricity in it
小題5:Which of the following is TRUE according to the passage?
A．There are four forces acting on the satellite.
B．The force of gravitation makes the satellite go round and round.
C．As time goes by, the satellite will finally fall down.
D．The satellite will stay in space forever.

小題1:D
小題2:A
小題3:A
小題4:B
小題5:C
短文屬于說明文。介紹了人造衛(wèi)星不會墜落的原理。
小題1:細節(jié)理解題。從第一段第二句“…are used for communication, weather monitoring and research.”可知沒提到D項。
小題2:推理判斷題。從第二段最后一句“The gravitational pull of the earth”可知地心引力來自于地球。
小題3:綜合理解題。從第二段第二句“…tries to pull the satellite towards the earth”和最后一句“…keeps the satellite from flying away”可知：是因為地心引力。
小題4:細節(jié)理解題。從短文后兩句“…loses its speed…crash down to the earth”可知。
小題5:綜合理解題。通讀全文，可知A、B、D三項不符合文意；C項與短文最后一段吻合。
練習冊系列答案
相關(guān)習題

科目：初中英語 來源：不詳 題型：閱讀理解


If you do not use your arms or your legs for some time, they will become weak, and when you start using them again, they slowly become strong again. Everybody knows that. Yet many people do not seem to know that memory works in the same way.
When someone says that he has a good memory, he really means that he keeps his memory in practice by using it. When someone else says that his memory is poor, he really means that he does not give it enough chance to become strong.
If a friend says that his arms and legs are weak, we know that it is his own fault. But if he tells us that he has a poor memory, many of us think that his parents may be blamed, and few of us know that it is just his own fault (過錯). Have you ever found that some people can't read or write but usually they have better memories? This is because they cannot read or write and when they have to remember things, they cannot write them down in a small notebook. As a result, they have to remember days, names, songs and stories, so their memory is being exercised the whole time.
So if you want to have a good memory, learn from the people: practice remembering things in a way as other people do.
小題1:Someone can't have a good memory if ________.
A．he can't read or write
B．his parents haven't a good memory
C．he doesn't make good use of his memory
D．he doesn't use his arms or legs for some time
小題2:If you do not use your arms or legs for some time, ________.
A．they will become thin
B．they will become weak
C．they begin to ache all over
D．you can't use them any more
小題3:Which of the following statements is true?
A．Your memory needs chance for practice.
B．A good memory is inherited(遺傳) from parents.
C．Your memory works in the different ways as your arms or legs.
D．Don't learn to read and write if you want to have a good memory.
小題4: Few people know that if someone has a poor memory it is ________.
A．his own faultB．his parents' fault
C．his teachers' faultD．his friends' fault
小題5: The writer wants to tell us ________.
A．how to read and write well
B．how to have a good memory
C．how to use our arms or legs better
D．how to learn from the people who can't read or write

查看答案和解析>>

科目：初中英語 來源：不詳 題型：完形填空

Waste can be seen everywhere in the school. Some students ask for more food  26  they can eat and others often forget   27  the light when they leave the classroom.
Waste can   28  a lot of problems. Although China is rich    29  some resources(資源), we are short for others, for example, fresh water. It is said that we will have   30   coal or oil to use in 100 years. So if we go on 31  our resources, what can we use in the future? Think about it.
In our daily life, we can do   32  things to stop waste, for example, turn off the water taps when we finish  33  it, try not to throw so much rubbish, and so on. Little by little,   34  will be changed. Waste can stopped one day if we do   35   best. I hope we can.
小題1:
A．thanB．a(chǎn)sC．likeD．a(chǎn)nd
小題2:
A．to turn offB．turning offC．to turn onD．turning off
小題3:
A．bingingB．broughtC．bringD．brings
小題4:
A．inB．forC．ofD．a(chǎn)bout
小題5:
A．notB．manyC．noD．much
小題6:
A．wastedB．wastesC．wasteD．wasting
小題7:
A．muchB．manyC．fewD．little
小題8:
A．usedB．to useC．usingD．use
小題9:
A．everythingB．a(chǎn)nythingC．nothingD．something
小題10:
A．usB．oursC．ourD．ourselves

查看答案和解析>>

科目：初中英語 來源：不詳 題型：閱讀理解

We are all learning English, but how can we learn English well? A student can know a lot about English, but maybe(可能) he can’t speak English. If you want to know how to (如何) swim, you must get into the river. And if you want to be a football player, you must play football.
So, you see. You can learn English only by(通過) using(使用)it. You must listen to your teacher in class. You must read your lessons every day. You must speak English to your classmates and also you must write something sometimes. Then one day, you may find your English very good.
小題1:You know a lot about English but maybe you       
A．can speakB．can study it
C．can’t study itD．can’t use it
小題2:If you want to learn to swim you should         
A．gets into the river
B．read books about swimming
C．learn from other people first
D．play football well first
小題3:If you want to be a football player, you should        
A．buy a good football
B．play football
C．watch others play football
D．put your football away
小題4:The story of learning swimming and playing football tells us       
A．we learn English by using it
B．swimming needs water
C．playing football is easy
D．learning English is difficult
小題5:If you want to study English well, you must often        
A．speak EnglishB．write in English
C．listen to EnglishD．A, B, and C

查看答案和解析>>

科目：初中英語 來源：不詳 題型：閱讀理解

Rivers are one of our most important natural resources(資源). Many of the world’s great cities are located on rivers, and almost every country has at least one river running through it that plays an important part in the lives of its people.
Since the beginning of history, people have used rivers for transportation. The longest one in the United States is the Mississippi. The lifeline of Egypt is the Nile. To the people of India, the Ganges is great, but it is also important for transportation; ships can travel along it for a thousand miles. Other great rivers are the Congo in Africa and the Mekong in southeastern Asia. The greatest of all for navigation（航海）, however, is the Amazon in Brazil（巴西）. It is so wide and so deep that large ships can go about two thousand miles up it.
Besides transportation, rivers give food to eat, water to drink, water for crops, and chances for fun. In order to increase the supply(供給) of water for crops, engineers sometimes build a dam (大壩)across a river and let a lake form behind the dam. Then people can use the water not only to irrigate(灌溉) their fields but also to make electricity for their homes and industries.
However, large cities and industries that are located on rivers often cause problems. As the cities grow in size and industries increase in number, the water in the rivers becomes polluted with chemicals and other materials. People are learning the importance, however, of doing more to keep their rivers clean if they want to enjoy the benefits of these natural resources.
小題1:The greatest river for navigation is ________________.
A．the MississippiB．the Nile
C．the MekongD．the Amazon
小題2:Which is NOT true according to the passage?
A．Many cities are located on rivers.
B．Almost every country has at least one important river.
C．The Nile is in India.
D．Rivers play an important part in the lives of people.
小題3:When rivers are dammed, people use the water for __________.
A．keeping the rivers clean
B．making electricity
C．washing clothes
D．irrigation and the production of electricity
小題4:Most water in rivers is polluted with ___________.
A．people’s drinking water too much
B．people’s swimming in the river too much
C．chemicals and other materials
D．people’s building a dam across a river
小題5:The best title for the passage is _____________.
A．The Importance of RiversB．Rivers in Cities
C．TransportationD．Natural Resources

查看答案和解析>>

科目：初中英語 來源：不詳 題型：閱讀理解

Comets(彗星) are parts of our solar system. Like the planets, they go around the sun.
But comets are not made of solid rocks like planets. A comet is a ball of dust, stones, and ice. Many people call comets dirty snowballs.
The “snowball” may be only a few miles across. But when the sun heats the “snowball,” much of it is changed to gases. The gases spread out and form the comet’s head, which may be thousands of miles across.
A comet moves fast in its trip around the sun. But when we see it, the comet does not seem to move. That’s because it is so far away. The moon moves fast, but when you look at it, you can’t see any motion(運動). That’s because the moon is far away.
Each year astronomers(天文學家) discover new comets. Some of them are seen only once. They make one trip around the sun and then go away out into space. The sun’s gravity cannot hold them.
Other comets, like Halley, keep returning. They have been captured by the sun. Halley’s earliest visit was probably 3,000 years ago. It may keep returning for another 3,000 years.
But every time a comet goes around the sun, the comet loses part of itself. Gases and dust are pulled out of the comet. That’s why Halley is now dimmer（暗淡的） than it used to be. Next time it visits us, in 2062, it may be even dimmer. Each visit it may get dimmer and dimmer, until it finally disappears.
小題1:What is this passage mostly about?
A．Comets and the sun.
B．Why comets are like snowballs.
C．Who discovered the first comet.
D．Facts about comets.
小題2:How does the writer help the reader understand what a comet looks like?
A．By telling about a famous one.
B．By explaining how far away it is.
C．By describing how fast it moves.
D．By describing it as a dirty snowball.
小題3:What is the most likely reason the writer wrote this passage?
A．To give information about comets.
B．To tell readers about famous comets.
C．To explain the importance of comets.
D．To encourage readers to look for comets.

查看答案和解析>>

科目：初中英語 來源：不詳 題型：閱讀理解

Taking away a city’s rubbish is a big job. Every day trucks come into a city to collect it. Most rubbish is made up of things we can’t eat or use. If we kept these things we would soon have a mountain of rubbish.
In some cities the rubbish is collected and taken outside of the city to a dump(垃圾站). Often the city dump is placed where the ground is low or there is a big hole. The kitchen rubbish is broken into small pieces and sent into the sewage system. The sewagesystem takes away the used water from toilets, bathtubs(澡盆) and other places.
To keep mice and flies away, some earth is used to cover the newly dumped rubbish. Later, grass may be planted on the rubbish-filled land. Finally, a house or a school may be built there, and then you’d never know that this had once been an old rubbish dump.
In other cities the rubbish is burnt in special places. The fire burns everything but the metal. Sometimes the metal can be used again in factories where things are made of metal. The food parts of rubbish are put in special piles where they slowly change into something called humus(腐殖土), which looks like black earth. It is rich with kinds of things that feed plants and help make them grow.
小題1:You can most probably read the passage in _______.
A．a(chǎn) history bookB．a(chǎn) TV guide
C．a(chǎn) science bookD．a(chǎn) telephone book
小題2:The underlined word “sewage” in the passage means_______.
A．排污B．染色C．洗滌D．吸塵
小題3:According to the passage, the food parts of rubbish can be used again_______.
A．to feed animals
B．to feed plants
C．to build a house
D．to make machines
小題4:How should we take care of a used metal box according to the passage?
A．By burning it off.
B．By putting it in water.
C．By throwing it away.
D．By reusing and recycling it.

查看答案和解析>>

科目：初中英語 來源：不詳 題型：閱讀理解

The widespread number of food scandals(丑聞)in  China is making many people pause before they put their chopsticks in their mouths．They are wondering if the food they are eating is clean，healthy and nutritious(營養(yǎng)) or does it contain（包含） something harmful that will cause disease?
Most of the food we eat today is processed food(加工食品)．That means the foods we buy in stores and supermarkets，especially packaged foods，are prepared in factories．Chemicals are added to the foods in these factories to  make them look better，taste better and last longer on the shelf．The chemicals are supposed to be harmless and there are laws that regulate(控制) which chemicals can and cannot be used．Unfortunately，some producers do not obey the laws．
A producer of steamed buns(饅頭)in Zhejiang Province was recently discovered to be breaking the law．He was adding yellow dye and other banned chemicals to the buns．He was also taking old buns and using them to make new buns．Most of the buns were sold to schools and eaten by students…like you!
Why did he do it? Why did he break the law and endanger people’s  health? The answer is simple：he wanted to make more money．It was a moral failing，and this is at the heart of the food scandals in China．Too many people focus on making money and not on the effects their actions can have on others．
小題1:Chemicals are added to the foods in the factories because
A．they want to make the foods look better，taste better and last longer
B．they want to make the foods contain something harmful
C．chemicals will cause disease D．chemicals are harmless
小題2:According to the passage，which is NOT true?
A．Most of the food we eat today is prepared in factories．
B．There are laws that regulate which chemicals can and cannot be used．
C．The food scandals in China are making many people worry about the food safety．
D．Most of the buns were sold to schools and eaten by students in Zhejiang Province．
小題3:It was a moral failing，and this is at the heart of the foodscandals in China．Here what’s the Chinese meaning of“moral failing”?
A．精神崩潰B．道德滑坡C．質(zhì)量下降D．心理失衡
小題4:What is the main reason of the food scandals in China ?
A．Some products do not obey the laws.
B．The processed food is clean, healthy and nutritious.
C．Too many people pay attention to making money.
D．The chemicals are supposed to be harmless and can be used.
小題5:According to the passage, most of the buns were sold to_______ .
A．factoriesB．schoolsC．hospitalsD．companies

查看答案和解析>>

科目：初中英語 來源：不詳 題型：閱讀理解


When it was getting dark, a wolf was walking along the road. Then he was surprised to see his huge shadow(影子) under his feet.
“Wow, I didn’t know I was so big!” The wolf was happy to know it.
As time went by, the sun was going down and his shadow grew bigger and bigger, so it looked like a giant.
“Oh, look at my shadow. I’m so big!” The wolf thought that he was as big as his shadow. “I’m huge and excellent. I don’t need to be afraid of the lion.”
From then the wolf walked with his shoulders open. He thought of himself as the king of the forest.
“Why should I fear the lion? Lion! Come out! Here is your match（對手）.”It made the lion very angry, so he went to see the wolf.
“Here I am. I heard you said you could beat me. Now I’m here. Why don’t you prove it?”
The lion’s sharp claw(爪子) hit the wolf’s head hard. The wolf was knocked out. “Ah, help me!”
But it was too late when the wolf got to know that he wasn’t as big or strong as his shadow. Unluckily, he became the lion’s delicious supper.
小題1:. Why was the wolf so surprised?
A．He grew very quickly.B．He beat the other animals in the forest.
C．He saw his huge shadow.D．He didn’t need to be afraid of the lion any more.
小題2: What does the word “giant” in the passage probably mean?
A．大力士B．巨人C．怪獸D．野人
小題3:. The wolf went to the lion to________________.
A．send him some foodB．a(chǎn)sk for some food
C．tell him something surprisingD．show his strong body
小題4:. What was the result?
A．The lion ate the wolf.B．The wolf ate the lion.
C．They became good friends.D．The wolf became the king of the forest.
小題5:. Which one is the best title for this passage?
A．wolf and his shadowB．A wolf and a lion
C．The king of the forestD．A strong wolf

查看答案和解析>>

同步練習冊答案