It is believed that human story begins in Africa and ends about 200，000 years later with their seven billion descendants （后代） spread across the Earth，living in peace or at war，their faces lit by campfires and computer screens.
In between is an exciting tale of survival，movement，isolation，and conquest，most of it occurring before recorded history.Who were those first modern people in Africa？What routes did they take when they left their home continent 60，000 years ago to expand into Europe and Asia？When and how did humans reach the Americas？For decades，the only proof was found in a small number of scattered bones and artifacts that our ancestors left behind on their journeys.In the past 20 years，however，DNA technologies have allowed scientists to find a record of ancient human migrations in the DNA of living people.
"Every drop of human blood contains a history book written in the language of our genes，" says population geneticist Spencer Wells.The human genetic code，or genome，is 99.9 percent identical throughout the world.But while the bulk of our DNA is the same，what's left is responsible for our individual differences—in eye color or disease risk，for example.On very rare occasions，a small change，called a mutation，can occur，which is then passed down to all of that person's descendants.Generations later，finding that same mutation in two people's DNA indicates that they share the same ancestor.By comparing mutations in many different populations，scientists can trace their ancestral connections.
These ancient mutations are easiest to track in two places：in DNA that is passed from mother to child （called mitochondrial DNA，or mtDNA for short），and in DNA that travels from father to son （known as the Y chromosome，the part of DNA that determines a child will be a boy）.By comparing the mtDNA and Y chromosomes （染色體） of people from various populations，geneticists can get a rough idea of where and when those groups separated in the great migrations around the planet.
（1）The best title for this reading could be " DD"．
A．Exploring Human History
B．Finding DNA Differences
C．Making a Biology Experiment
D．Discovering Ancestries in DNA
（2）What can we infer from the quote of Spencer Wells in Paragraph 3？ AA
A．A drop of blood contains genetic information that can tell a person's ancestral history.
B．The organization of information in a history book is similar to the organization of DNA within a gene.
C．Every drop of blood contains enough DNA information to fill many history books.
D．Although people speak different languages，all human blood contains the same language.
（3）The underlined word "bulk" in Paragraph 3 most probably means BB．
A．the large size
B．the main part
C．the weight or shape
D．the quantity
【答案】D；A；B
【解答】
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發(fā)布：2024/4/28 8:51:19組卷：0引用：2難度：0.5
相似題
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1．It is widely believed that biodiversity（生物多樣性）is promoted to save species.But in reality species exist only as part of ecosystems and cannot survive unless their ecosystems are protected along with as much as possible of the diversity they contain.
Protecting habitats（棲息地）is important for keeping biodiversity.In 2003，over 102，000 habitats covering nearly 19 million square kilometres，or 11.5% of the world's land surface，were under some form of protection.Though this is a great improvement since 1962，when just 1，000 protected habitats were listed，it is still not considered enough to stop the ecocide that is endangering the world's biodiversity.
For a number of environmentalist，protecting the world's 25 biodiversity hotspots（熱點(diǎn)地區(qū)）is critical to saving habitats and species.But many hotspots are endangered already，having lost up to three-quarters of their original plants.
The poor state of most biodiversity hotspots results directly from population growth and migration（遷移） into these areas.A study found that by the mid-1990s around 1.1 billion people lived in these hotspots.Moreover，the annual population growth rate in these areas was 1.8%，higher than the global average of 1.4%.The PAI report concluded that human-related environmental changes will continue to put pressure on hotspots.Therefore，keeping biodiversity requires paying close attention to population size.
Protecting hotspots is not simply a matter of putting up fences and employing guards.The best results are achieved when local people are educated about the value of wildlife，and actually gain a share of the benefits from eco-tourism.Only then do they have a chance to see the benefits of protecting hotpots.
（1）What can we infer from paragraph 1？
A．The loss of any species can affect humans.
B．Endangered species are paid more attention to by humans.
C．Species can still survive when their ecosystems are destroyed.
D．Ecosystem protection is as important as diversity protection.
（2）What does the underlined word "ecocide" in paragraph 2 mean？
A．Ecosystem protection.
B．Reduction of the number of species.
C．Serious damage to habitats.
D．Habitats protection.
（3）What's the direct cause of the terrible state of the hotspots？
A．Population growth in hotpots.
B．Migration out of these areas.
C．Global warming.
D．The global average population growth rate.
（4）What's the author's opinion on protecting the hotspots？
A．It's simple to carry out.
B．It leads to the increase of tourists.
C．It's closely connected with local people.
D．It suggests that the local people are well educated.發(fā)布：2025/1/6 16:30:6組卷：0引用：1難度：0.5 -
2．International students who stayed in the US as their classes moved online during the COVID may be forced to leave，following guidelines of the US Immigration and Customs Enforcement published due to the pandemic（流行?。?
"You know I don't want to put my family at risk，I don't want to put myself at risk to travel during a pandemic and go back to Pakistan，and even if I could delay the program for a year，it is not certain that I will get the visa again." said a Pakistani student.
Many students say they need to be in the US for more than attending cljye.ais.As a PhD student，the library is an extremely important resource for them，although it is because of COVED that those services have been closed，which means even this advantage is gone.
"You know more than 90% of the international students who were studying the US when COVID-19 hit and college campuses were closed have to remain in the US and this creates such trouble in their lives and such uncertainty that is unreasonable." said a lady from a university.
International students staving in the United States say the new ruling has disturbed their plans to return. "I know it is a fact that when it comes to rules，guidelines，laws and stuff like that，international students are sort of treated as low-level citizens.Even I can't even use the word "citizen" to begin with because that's what they make clear we are not."
The government said that the policy speaks for itself and that online coursework is not worth a visa.So far，not any sign of change has been within sight.As students are waiting for the policy to improve，their fall programming and their future remain in limbo.
（1）Why would international students prefer to stay in the US during the pandemic？
A．They couldn't delay the program for a year.
B．They can make full use of the library resource.
C．They wouldn't bring any potential danger to their family.
D．They can learn better with their classes moved online.
（2）What do international students staying in the United States think of the new rule？
A．The new rule treats them as American citizens.
B．The new rule shows great unreasonable opinion against them.
C．The new rule guides them to plan to return to the US.
D．The new rule treats them like low-level students in school.
（3）What is the government's attitude towards the new rule？
A．Favorable.
B．Neutral（中立）.
C．Unfavorable.
D．Unclear.
（4）What does the underlined phrase "in limbo" in the last paragraph mean？
A．Horrible.
B．Flexible.
C．Uncertain.
D．Unbelievable.發(fā)布：2025/1/6 15:30:8組卷：0引用：1難度：0.5 -
3．Most of us spend our lives seeking the natural world.We go fishing，sit in the garden，have a picnic，live in the suburbs or go to the seaside.The most popular leisure activity in Britain is going for a walk.When joggers jog，they don't run on the streets.Every one of them tends to go to the park or the river.
But despite this，our children are growing up naturedeprived（剝奪）.I spent my boyhood climbing trees.These days，children are robbed of the ancient freedom，due to problems like crime，traffic，the loss of the open space and strange new ideas about what is best for children，that is to say，things that can be bought，rather than things that can be found.
The truth is to be found elsewhere.A study in the US：families had moved to better housing and the children were assessed for ADHD—Attention Deficit Hyperactivity Disorder（注意力缺陷多動癥）.Those whose accommodation had more natural views showed an improvement of 19%；those who had the same improvement in material surroundings but no nice view improved just 4%.
ADHD is one of the great problems of modern childhood.One study after another indicates that contact with nature gives huge benefits to ADHD children.However，we spend money on drugs rather than on green places.
The life of old people is measurably better when they have access to nature.The increasing concern for the growing population of old people is in quality rather than quantity of years.And study after study finds that a garden is the single most important thing in finding that quality.Even problems with crime and aggressive behaviour are reduced when there is contact with the natural world.
We need the wild world.It is essential to our wellbeing，our health and our happiness.
（1）According to the author，people enjoyto seek nature.
A．jogging on the street
B．running in the gym
C．shopping in the supermarket
D．sitting in the garden
（2）From the second paragraph，we can see that.
A．Children don't want to approach nature
B．children probably spend less time in nature nowadays
C．climbing trees will certainly do good to the children
D．children tend to be happier as a result of their material satisfaction
（3）In what way do people benefit from their contact with nature？
A．Children with ADHD can be cured.
B．Children's performance at school is greatly improved.
C．Problems with crime and violent behavior will easily be solved.
D．A garden nearby improves the quality of old people's life.
（4）what is the main idea of this passage？
A．Access to nature improves our life.
B．Nature treats children for ADHD.
C．Getting close to nature reduces crime.
D．Man can't live without natural areas.發(fā)布：2025/1/6 16:30:6組卷：0引用：1難度：0.5
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