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题型:阅读理解-阅读单选 难度:0.65 引用次数:72 题号:15847986

Trees are able to defend themselves against diseases. They have both protective structures and protective processes. Thanks in large part to research done by Dr. Alex Shigo, we now know a great deal more about the way trees protect themselves than we did 50 years ago.

Just as our skin keeps harmful bacteria on the outside, bark (树皮) keeps out tree diseases. Since they can’t move around to avoid dangers, trees need thicker “skin” than we do. Living and non-living tissues protect tree trunks, roots, and branches from mechanical injury, drying out, and diseases.

But when something destroys this first line of defense — tears through the bark — what happens internally is interesting. When an injury occurs, a tree will transform some of its stored sugars to make masses of defensive chemicals, which are then distributed in a specific pattern internally around the wound. Dr. Shigo was the first to document this pattern, which he called CODIT — Compartmentalization (分室化) of Decay (腐烂) in Trees.

In making these CODIT compartments, trees form chemical walls to protect themselves from infection. The success of this walling-off process depends a lot on the species. Hard maple, for instance, can generate a strong CODIT response while species like soft maple achieve only an average level. Some, on the other hand, barely manage to form any chemical walls.

Overall tree vitality is another important factor. Even a hard maple may not be able to form strong chemical walls if it’s in a weak state. By definition, landscape trees are stressed as compared to their forest-living cousins. A street tree is worse off, faced with limited root space, air pollution, and more. The size of the injury also makes a difference. Even a healthy tree can have its defenses destroyed by a large wound.

Humans can help maximize trees’ defense capability by watering during dry seasons, keeping things out of the root zone, etc. In return, trees will help keep us in good health by offering shade, beauty, and companionship.

1. What will happen first if diseases come close to trees?
A.Infection will occur internally.B.Bark will provide protection
C.Chemical walls will take effect.D.Defense chemicals will be formed.
2. What does the author think of Dr. Shigo’s research?
A.Groundbreaking.B.Conservative.C.Ambiguous.D.Straightforward.
3. What does the author want to convey by mentioning hard maple in Paragraph 4?
A.Trees can form chemical walls
B.The size of the injury affects CODIT.
C.Trees cannot protect themselves if weakened.
D.The effectiveness of CODIT varies among species.
4. What can most likely be the best title of the passage?
A.The gift of the trees.B.The magic of CODIT.
C.The function of the bark.D.The self-preservation of the trees.
【知识点】 说明文 植物

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【推荐1】Great Theatres in the World

The Palais Garnier

Paris

The Palais Garnier is the best known theater of Paris. In 1669 Louis XIV gave a green light to the opera theater foundation in honor of the poet Pierre Perren and the composer Robert Kamber. Throughout centuries the theater changed its name and location several times up to the moment it appeared in Paris district in the nineteenth century.

Palace of Catalan Music

Barcelona

The Palace of Catalan Music in Barcelona is a quite young opera house founded in 1891. The facade (外观) of the Palace reminds that in Spain it is the place where the European and Arabian cultures connected closely.

But the main feature of the concert hall is its lighting. The illumination (照明) is completely natural. The Palace of Catalan Music’s roof is made of color glass fully. Lights of the sun create an indescribable effect!

Vienna State Opera

Vienna

Vienna State Opera was built in 1869. Its opening was marked by Mozart’s opera Don Juan. On the other hand, the building often became the object of severe criticism since it was built in extremely widespread neo-renaissance style.

La Scala Opera House

Milan

In 1776, the Milan architect Giuseppe Piermarini liked the piece of earth on the site of the destroyed Church of Santa Maria Della Scala. He decided to construct the opera theater on this place, which inherited (继承) the name of its ancestor building. The Europa Riconosciuta by the composer Antonio Salieri became the first opera of the La Scala theater.

1. Which theatre has the longest history?
A.The Palais Garnier.B.Palace of Catalan Music.
C.Vienna State Opera.D.La Scala Opera House.
2. What is most distinguished about Palace of Catalan Music?
A.Its location.B.Its adoption of natural light.
C.Its historical background.D.The styles of different periods.
3. What do Vienna State Opera and La Scala Opera House have in common?
A.They both received criticism.
B.They were both totally destroyed.
C.They were both constructed on the site of a church.
D.Their openings are both marked by shows of masterpieces.
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【推荐2】Across the rich world, well-educated people increasingly work longer than the less-skilled. Some 65% of American men aged 62-74 with a professional degree are in the workforce, compared with 32% of men with only a high-school certificate. This gap is part of a deepening divide between the well-education well off and the unskilled poor. Rapid technological advance has raised the incomes of the highly skilled while squeezing those of the unskilled. The consequences, for individual and society, are profound.
The world is facing as astonishing rise in the number of old people, and they will live longer than ever before. Over the next 20 years the global population of those aged 65 or more will almost double, from 600 million to 1.1 billion. The experience of the 20th century, when greater longevity translated into more years in retirement rather than more years at work, has persuaded many observers that this shift will lead to slower economic growth, while the swelling ranks of pensioners will create government budget problems.
But the notion of a sharp division between the working young and the idle old misses a new trend, the growing gap between the skilled and the unskilled. Employment rates are falling among younger unskilled people, whereas older skilled folk are working longer. The divide is most extreme in America, where well-educated baby-boomers (二战后生育高峰期出生的美国人) are putting off retirement while many less-skilled younger people have dropped out of the workforce.
That even the better-off must work longer to have a comfortable retirement. But the changing nature of work also plays a big role. Pay has risen sharply for the highly educated, and those people continue to reap rich rewards into old age because these days the educated elderly are more productive than the preceding generation. Technological change may well reinforce that shift: the skills that complement computers, from management knowhow to creativity. Do not necessarily decline with age.
1. what is happening in the workforce in rich countries?
A.younger people are replacing the elderly
B.well-educated people tend to work longer
C.unemployment rates are rising year after year
D.people with no college degree do not easily find work
2. what has helped deepen the divide between the well-off and poor?
A.Longer life expectancies
B.Profound changes in the workforce
C.rapid technological advance.
D.A growing number of well-graduated.
3. what do many observers predict in view of the experience of the 20th century?
A.Economic growth will slow down.
B.Government budgets will increase.
C.More people will try to pursue higher education
D.There will be more competition in the job market.
4. What is the result of policy changes in European countries?
A.Unskilled workers may choose to retire early.
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C.Even wealthy people must work longer to live comfortably in retirement.
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5. What is characteristic of work in the 21st century?
A.Computers will do more complicated work.
B.More will be taken by the educated young.
C.Most jobs to be done will be creative ones.
D.Skills are highly valued regardless of age.
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【推荐3】The cognitive health and development of boys may be affected by their mothers’ body mass index (BMI) (体重指数) while pregnant with them, according to research from Columbia University and the University of Texas at Austin.

The study, which was published in the journal BMC Pediatrics on Friday, observed 368 subjects from low-income African American and Dominican women during the second half of their pregnancies, and then evaluated their children three and seven years later. Researchers found that the sons of women whose BMIs indicated that they were overweight or obese when they became pregnant were more likely to show less developed athletic skills as 3-year-olds and lower intelligence as 7-year-olds compared to boys whose mothers were at “normal” weights during pregnancy.

Among boys, the study found, mothers’ overweight and obesity connected with IQ scores between 4.6 and almost 9 points lower than those of boys whose mothers’ weights were in the “normal” range before pregnancy. Researchers did not observe the same phenomenon among daughters whose mothers had been obese.

“These findings aren’t meant to shame or scare anyone,” Elizabeth Widen, assistant professor of nutritional sciences at UT Austin and one of the study’s co-authors, said in a press release. “We are just beginning to understand some of these interactions between mothers’ weight and the health of their babies.”

Why mothers’ obesity appeared to affect childhood IQ was unclear, but earlier research has suggested that there is a relationship between a mother’s diet and her child’s later IQ, according to Columbia University. Researchers did not control for what the mothers ate, the press release noted.

The study’s authors wrote that because childhood IQ has been shown to be an indicator of later success in life, studying how a mother’s obesity could affect the IQ of her child is worthwhile.

1. How did researchers carry out the study?
A.By measuring mothers’ body mass index.
B.By watching mothers and babies for years.
C.By comparing 3-year-old babies with 7-year-olds.
D.By evaluating the health of mothers and their babies.
2. What’s the main purpose of the study?
A.To show links between mothers’ weight and babies’ IQ.
B.To make those overweight mothers shameful and scared.
C.To warn some fat mothers to keep a balanced diet.
D.To persuade more obese mothers to lose weight.
3. What do the researchers think of the study?
A.Doubtful.B.Worrying.
C.Significant.D.Interesting.
4. In which section of a newspaper may the text appear?
A.Entertainment.B.Novel.
C.Education.D.Health.
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