Scientists have devised a way to determine roughly where a person has lived using a strand (缕) of hair, a technique that could help track the movements of criminal suspects or unidentified murder victims. The method relies on measuring how chemical variations in drinking water show up in people’s hair.

“You’re what you eat and drink, and that’s recorded in your hair,” said Thure Ceding, a geologist at the University of Utah.

While U.S. diet is relatively identical, water supplies vary. The differences result from weather patterns. The chemical composition of rainfall changes slightly as rain clouds move.

Most hydrogen and oxygen atoms in water are stable, but traces of both elements are also present as heavier isotopes (同位素). The heaviest rain falls first. As a result, storms that form over the Pacific deliver heavier water to California than to Utah.

Similar patterns exist throughout the U.S. By measuring the proportion of heavier hydrogen and oxygen isotopes along a strand of hair, scientists can construct a geographic timeline. Each inch of hair corresponds to about two months.

Ceding’s team collected tap water samples from 600 cities and constructed a map of the regional differences. They checked the accuracy of the map by testing 200 hair samples collected from 65 barber shops. They were able to accurately place the hair samples in broad regions roughly corresponding to the movement of rain systems.

“It’s not good for pinpointing (精确定位),” Ceding said. “It’s good for eliminating many possibilities.” Todd Park, a local detective, said the method has helped him learn more about an unidentified woman whose skeleton was found near Great Salt Lake. The woman was 5 feet tall. Police recovered 26 bones, a T-shirt and several strands of hair. When Park heard about the research, he gave the hair samples to the researchers. Chemical testing showed that over the two years before her death, she moved about every two months. She stayed in the Northwest, although the test could not be more specific than somewhere between eastern Oregon and western Wyoming. “It’s still a substantial area,” Park said. “But it narrows its way down for me.”

1. What is the scientists’ new discovery?

A. One’s hair growth has to do with the amount of water they drink.

B. A person’s hair may reveal where they have lived.

C. Hair analysis accurately identifies criminal suspects.

D. The chemical composition of hair varies from person to person.

2. What does the author mean by “You’re what you eat and drink” (Line 1, Para. 3)?

A. Food and drink affect one’s personality development.

B. Food and drink preferences vary with individuals.

C. Food and drink leave traces in one’s body tissues.

D. Food and drink are indispensable to one’s existence.

3.What is said about the rainfall in America’s West?

A. There is much more rainfall in California than in Utah.

B. The water it delivers becomes lighter when it moves inland.

C. Its chemical composition is less stable than in other areas.

D. It gathers more light isotopes as it moves eastward.

4. What did Ceding’s team produce in their research?

A. A map showing the regional differences of tap water.

  B. A collection of hair samples from various barber shops.

  C. A method to measure the amount of water in human hair.

  D. A chart illustrating the movement of the rain system.

5. What is the practical value of Ceding’s research?

A. It helps analyze the quality of water in different regions.

  B. It helps the police determine where a crime is committed.

  C. It helps the police narrow down possibilities in detective work.

  D. It helps identify the drinking habits of the person under investigation.

第二部分:阅读理解(第一节20小题,第二节5小题;每小题2分,满分50分)

第一节:阅读下列短文, 从每题所给的四个选项 (A、B、C和D) 中, 选出最佳选项。

I'm from the South Bronx. At 7, my neighborhood was the beginning and end of my universe. It was a small town to me. Everyone knew each other, so if you got into trouble in school, chances are your mom knew about it before you got home. I felt watched over and safe.

But just before I turned 8, things began to change. I watched two buildings on my block burn down. I remember seeing my neighbor Pito go up and down the fire escape to get people out. Where were the firemen? Where was the truck? Somebody must have called them.

That same summer, after serving two tours in Vietnam, my brother was killed in the South Bronx. He was shot above the left eye and died instantly.

People who could moved out of the neighborhood, and all I wanted to do was get out, too. I used education to get away from there and got good at avoiding the topic of where I was from. To be from the South Bronx meant that you were not a good person. It felt like a stain.

After college, I didn't want to come back to the South Bronx, but in order to afford graduate school, I had to. I was almost 30 and could only afford to live at my parents' home. It felt like a defeat, and I hated it.

At the same time, the city was planning a huge waste facility here, and no one seemed to care — including many of us who lived here. They were like, "Well, it's a poor community; what's the difference?"

I was very angry. It drove me to act. It moved my spirit in a way that I didn't know was possible. And it changed my beliefs — it changed the way I felt about myself and my community. I worked hard with others who felt the same way, and together, we defeated the plan.

After that, I realized it's just as important to fight for something as it is to fight against something. So we dreamed up a new park on the site of an illegal waste dump — and after many community clean-ups, along with $3 million from the city, we have one. And it's a glory. It was the seed from which many new plans for our community have grown.

Today, the South Bronx is no longer a stain; it's a badge(象征) of honor for me. I believe that where I'm from helps me to really see the world. Today, when I say I'm from the South Bronx, I stand up straight. This is home, and it always will be.

1Paragraphs 2 and 3 make the readers believe ____________.

A. the author felt watched over and safe

B. he author’s brother was a bad man

C. the author’s neighbor Pito was braver than a fireman

D. the author felt his hometown was not a safe place to live in

2.The author went back to the South Bronx after college because ____________.

A. he couldn’t afford to live without his parents’ help

B. he loved his hometown very much

C. he was defeated in studies at college

D. he almost reached the age of 30

3.The underlined sentences(Paragraph 2) imply that ____________.

A. the author wondered where the firemen and the truck were

B. the author wanted someone to call the firemen

C. the firemen didn’t come to help although called

D. the firemen didn’t find a place to park the truck

4.What does the author want to convey in the passage?

A. Great changes have taken place in the South Bronx.

B. The South Bronx is a beautiful place.

C. You can make a difference to your hometown if you act.

D. Everyone should love his hometown.

 0  25941  25949  25955  25959  25965  25967  25971  25977  25979  25985  25991  25995  25997  26001  26007  26009  26015  26019  26021  26025  26027  26031  26033  26035  26036  26037  26039  26040  26041  26043  26045  26049  26051  26055  26057  26061  26067  26069  26075  26079  26081  26085  26091  26097  26099  26105  26109  26111  26117  26121  26127  26135  151629 

违法和不良信息举报电话:027-86699610 举报邮箱:58377363@163.com

精英家教网