Did you ever wonder why leaves change colors in autumn, or how it happens? Here’s a quick explanation.
First of all, you’ve probably noticed that not all trees lose their leaves. There are two major types of trees: deciduous trees and evergreens. Evergreens keep their leaves and stay green all year long. The deciduous trees are the ones that lose their leaves each year.
In autumn, the days begin to get shorter. The sun is also lower in the sky at noon, which causes temperatures to be cooler. The combination of less sunshine and lower temperatures is what causes the deciduous trees to drop their leaves. In winter, deciduous trees “go to sleep”, sort of like a bear goes into hibernation.
Leaves are the food factories for a plant. Unlike animals，plants make their own food by taking energy directly from the sun. Plants do this by using a chemical in their leaves called chlorophyll.
Chlorophyll is green. During the spring and summer the leaves of a deciduous tree look green because there is a lot of chlorophyll there. In autumn, however, the sunshine becomes more scarce and the leaves on the trees stop making new chlorophyll. As the old chlorophyll starts to break down, the green color of the leaf begins to go away.
You’ve probably also noticed that the leaves of different kinds of trees change different colors. The leaves of some trees turn yellow or orange, while the leaves of other trees turn bright red or purple. The different colors are caused by the different chemical reactions that are happening in the leaves.
For example, the leaves of some trees turn yellow when the chlorophyll breaks down. When the green chlorophyll goes away, a yellow pigment in the leaf becomes visible. The yellow pigment, called cartenoid, was already there during the summer, but is was not easily seen because there was too much green chlorophyll.
In other trees where the leaves turn red or purple a different chemical reaction takes place. In those leaves the chlorophyll also breaks down, but another chemical reaction takes place at the same time. Chemicals in the leaves, called starches, begin to change into chemicals called anthocyanins, which give the leaves their red and purple colors.
So next time you see the beautiful colors of autumn you will also know the science behind that beauty.
46. What is the correct term for trees that lose their leaves in the autumn?
A. Evergreens B. Deciduous C. Cartenoids D. Anthocyanins
47. Which of the following is NOT mentioned as a cause of trees dropping their leaves?
A. A change in temperature B. The amount of daylight available
C. Extra chlorophyll D. Chemical changes in the leaves
48. If there are 50 evergreens and 10 deciduous trees in a forest, in autumn what color are most of the leaves in the forest likely to be?
A. Green B. Red and purple
C. Yellow D. not enough information to determine the answer
49. Which of the following is only present in leaves during the autumn?
A. Chlorophyll B. Starch C. Cartenoids D. Anthocyanins
50. Where would such an article mostly likely be published?
A. In a book B. In a primary school science text book
C. In a magazine for young people D. All are equally likely
科目：高中英语 来源： 题型：阅读理解
We can achieve knowledge either actively or passively（被动地）. We achieve it actively by direct experience, by testing and proving an idea, or by reasoning.
We achieve knowledge passively by being told by someone else. Most of the learning that takes place in the classroom and the kind that happens when we watch TV or read newspapers or magazines is passive. Although we are used to passive learning, it’s not surprising that we depend on it in our everyday communication with friends and co-workers.
Unfortunately, passive learning has a serious problem. It makes us tend to accept what we are told even when it is rumor (谣言).
Did you ever play the game Rumor? It begins when one person writes down a message but doesn’t show it to anyone. Then the person whispers it, word for word, to another person. That person, in turn, whispers it to still another, and so on. Then the last person writes down the message word for word as he or she hears it. Then the two written statements are compared. Typically, the original message has changed.
That’s what happens in daily life. The simple fact that people repeat a story in their own words changes the story. Then, too, most people listen imperfectly. And many enjoy adding their own feelings to a story, trying to improve it, marking it with their own personal style. Yet those who hear it think they know.
This process is also found among scholars and authors: A statement of opinion by one writer may be re-stated as fact by another, who may in turn be quoted by yet another; and this process may continue, unless it occurs to someone to question the facts on which the original writer based his opinion or to challenge the interpretation he placed upon those facts.
According to the passage, passive learning may occur when a person is _______.
A. doing a medical experiment B. solving a math problem
C. watching news on TV D. doing scientific reasoning
The underlined word “it” in Paragraph 2 refers to _____.
A. active learning B. knowledge C. communication D. passive learning
The author mentions the game Rumor to show that _____.
A. a message may be changed when being passed on
B. a message should be delivered in different ways
C. people may have problems with their sense of hearing
D. people tend not to believe in what they know as rumor
What can we infer from the passage?
A. Active learning is less important.
B. Passive learning may not be dependable.
C. Active learning occurs more frequently.
D. Passive learning is not found among scholars.
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科目：高中英语 来源：2012-2013学年海南琼海嘉积中学高一下学期教学质量监测英语卷（带解析） 题型：阅读理解
Did you ever look up at the moon and think you saw a man’s face there? When the moon is round and full, the shadows(影子) of the moon mountains and the lines of the moon valleys sometimes seem to show a giant nose and mouth and eyes. At least, some people think so.
If there were a man on the moon—instead of mountains and valleys that just look like the face of a man—what would he be like?
He would not be like anyone you know. He would not be like anyone anybody knows.
If the man on the moon were bothered by too much heat or cold the way Earth people are, he could not stay on the moon.
The moon becomes very, very hot. It becomes as hot as boiling water. And the moon becomes very, very cold. It becomes colder than ice.
Whatever part of the moon the sun shines on is hot and bright. The rest of the moon is cold and dark.
If the man on the moon had to breathe to stay alive, he couldn’t live on the moon because there’s no air there. He’d have to carry an oxygen tank, as astronauts do. There’s no food on the moon, either. Nothing grows—not even weeds（grass）.
If the man on the moon liked to climb mountains, he would be very happy. There are many high places there, such as the raised land around the holes, or craters(火山口), of the moon. Some of these rims are as tall as Earth’s highest mountains.
But if the man on the moon liked to swim, he would be unhappy. There is no water on the moon—just dust and rock.
When you think of what it’s like on the moon, you may wonder why it interests our scientists. One reason is that the moon is Earth’s nearest neighbor—it is the easiest place in space to get to.
Going back and forth between the moon and Earth, astronauts will get a lot of practice in space travel. Things learned on moon trips will be of great help to astronauts who later take long, long trips to some of the planets.
Scientists are also interested in the moon because it has no air. The air that surrounds Earth cuts down the view of the scientists who look at the stars through telescopes. A telescope on the moon would give them a clearer, closer view of the stars.（words: 411）
【小题1】What is the reason why our scientists are interested in the moon.?
| A．The moon is beautiful. |
| B．The moon is different from the earth. |
| C．The moon is Earth’s nearest neighbor—it is the easiest place in space to get to. |
| D．The moon is the easiest place in space to get to and it has no air, unlike Earth. |
| A．ball | B．hill | C．round edge | D．height |
| A．We can learn much from research on the Moon. |
| B．There may be human beings on the moon. |
| C．If there were a man on the Moon, there would be many similarities between the man on the Moon and on the Earth. |
| D．A telescope on the Moon would help scientists have a clearer, closer sight of the stars. |
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科目：高中英语 来源：2012-2013学年内蒙古呼伦贝尔牙林一中高一上学期期中考试英语试卷（带解析） 题型：阅读理解
Although English is not as old as Chinese , it is spoken by many people around the world every day. English speakers are always creating new words and we are often able to know where most words come from.
Sometimes, however, no one may really know where a word comes from. Did you ever think about why hamburgers are called hamburgers, especially when they are not made with ham? About a hundred years ago, some men went to America from Europe. They came from a big city in Germany called Hamburg. They didn’t speak good English, but they ate good food. When some Americans saw them eating round piece of beef, they asked the Germans what it was. The Germans didn’t understand the question and answered, “We come from Hamburg.” One of these Americans owned a restaurant, and had an idea. He cooked some round piece of bread and started selling them. Such bread came to be called “hamburgers”. Today, “hamburgers” are sold in many countries around the world.
Whether this story is true or not, it certainly is interesting. Knowing why any word has a certain meaning is interesting, too. This reason, for most English words, can be found in any large English dictionary.
【小题1】Hamburg is ____________
| A．a kind of food | B．a round piece of beef |
| C．the name of a village | D．a city in Germany |
| A．few Americans like hamburgers |
| B．hamburgers are made with beef |
| C．hamburgers are made with ham |
| D．hamburgers were first sold about a century ago |
| A．Where all the new words come from. |
| B．Where those Germans came from. |
| C．The reason why a word has a certain meaning. |
| D．The reason why English is spoken around the world. |
| A．China because it has a long history |
| B．English because Germans don’t speak good English |
| C．The round piece of beef which those people from Hamburg were eating |
| D．English speakers because they always create new words |
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科目：高中英语 来源：2014届河北高阳中学第一次月考英语卷（解析版） 题型：信息匹配
根据短文内容，从短文后的选项中选出能填入空白处的最佳选项。选项中有两项为多余选项。
Why Exercise Is Cool?
1. Exercise Strengthens Muscles
Did you ever do a push-up or swing across the monkey bars at the playground? 1. By using your muscles to do powerful things, you can make them stronger. For older teens and adults, this kind of workout can make muscles bigger, too.
2. 2.
Can you touch your toes easily without yelling ouch? Most kids are pretty flexible, which means that they can bend and stretch their bodies without much trouble. Being flexible is having “full range of motion,” which means you can move your arms and legs freely without feeling tightness or pain.
3. Exercise Keeps the Balance
3. Your body needs a certain amount of calories every day just to function, breathe, walk around, and do all the basic stuff. 4. If you’re not very active, your body won’t need as many calories.
Whatever your calorie need is, if you eat enough to meet that need, your body weight will stay about the same. If you eat more calories than your body needs, it may be stored as extra fat.
4. Exercise Makes You Feel Good
It feels good to have a strong, flexible body that can do all the activities you enjoy—like running, jumping, and playing with your friends. It’s also fun to be good at something, like scoring a basket, hitting a home run, or perfecting a dive.
But you may not know that exercising can actually put you in a better mood. 5. It’s just another reason why exercise is cool!
A. So you want to do some aerobic (有氧的) exercise right now?
B. Food gives your body fuel in the form of calories, which are a kind of energy.
C. When you exercise, your brain releases a chemical, which may make you feel happier.
D. Those are exercises that can build strength.
E. Exercise Makes You Flexible
F. Exercise Makes Your Heart Happy
G. But if you’re active, your body needs an extra measure of calories or energy.
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科目：高中英语 来源：2015届四川省高一上学期期中考试英语试卷（解析版） 题型：阅读理解
Although English is not as old as Chinese, it is spoken by many people around the world every day. English speakers are always creating new words, and we should be able to know where most words come from.
Sometimes, however, no one may know really where a word comes from. Did you ever think about why hamburgers are called hamburgers, especially when they are not made with ham( 火腿 )? About a hundred years ago, some men went to America from Europe. They came from a big city in Germany called Hamburger. They didn’t speak good English, but they ate good food. When some Americans saw them eating round pieces of beef, they asked the Germans what it was. The Germans did not understand the question and answered. “We came from Hamburger.” One of these Americans owned a restaurant, and had an idea. He cooked some round pieces of beef like what the men from Hamburger ate. Then he put them between two pieces of bread and started selling them. Today “ hamburgers” are sold in many countries around the world.
Whether this story is true or not, it certainly is interesting. Knowing why any word has a certain meaning is interesting, too. The reason may be found in any large English dictionary.
1.According to the writer, English ______.
A．is as old as Chinese B．is not so old as Chinese
C．is older than German D．is very difficult to learn
2.According to the story,_______.
A．few Americans like hamburgers
B．hamburgers are made with beef
C．hamburgers are made with ham
D．hamburgers were sold all over the world about a century ago
3.According to the writer, which of the following can be found in any large English dictionary?
A．Where all the new words come from
B．Where those Germans came from
C．The reason why any word has a certain meaning.
D．The reason why English is spoken around the world
4.According to the story, the word “hamburger” comes from ________.
A．China because it has a long history
B．England because Germans don’t speak good English
C．the round pieces of beef those people from Hamburger brought to America
D．English speakers because they always create new words
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