When people first walked across the Bering Land Bridge thousands of years ago, dogs were by their sides, according to a study published in the journal Science.
Robert Wayne of the University of California, Los Angeles, and Jennifer Leonard of the Smithsonian Institute, used DNA material—some of it unearthed by miners in Alaska—to conclude that today’s domestic dog originated in Asia and accompanied the first humans to the New World about 10,000 to 15,000 years ago. Wayne suggests that man’s best friend may have enabled the tough journey from Asia into North America. “Dogs may have been the reason people made it across the land bridge,” said Wayne. “They can pull things, carry things, defend you from fierce animals, and they’re useful to eat.”
Researchers have agreed that today’s dog is the result of the domestication(驯化) of wolves thousands of years ago. Before this recent study, a common thought about the precise origin of North America’s domestic dog was that Natives domesticated local wolves, the descendents(后代) of which now live with people in Alaska, Canada, and the Lower 48.
Dog remains from a Fairbanks-area gold mine helped the scientists reach their conclusion. Leonard, an evolutionary biologist, collected DNA from 11 bones of ancient dogs that were locked in permafrost(永冻层) until Fairbanks miners uncovered them in the 1920s. The miners donated the preserved bones to the American Museum of Natural History in New York City, where they remained untouched for more than 70 years. After borrowing the bones from the museum, Leonard and her colleagues used radiocarbon techniques to find the age of the Alaska dogs. They found the dogs all lived between the years of 1450 and 1675 A.D., before Vitus Bering and Aleksey Chirikov who were the first known Europeans to view Alaska in 1741. The bones of dogs that wandered the Fairbanks area centuries ago should therefore be the remains of “pure native American dogs,” Leonard said. The DNA of the Fairbanks dogs would also expose whether they were the descendents of wolves from North America.
Along with the Fairbanks samples, the researchers collected DNA from bones of 37 dog specimens(标本) from Mexico, Peru, and Bolivia that existed before the arrival of Columbus. In the case of both the Alaska dogs and the dogs from Latin America, the researchers found that they shared the most genetic material with gray wolves of Europe and Asia. This supports the idea of domestic dogs entering the New World with the first human explorers who wandered east over the land bridge.
Leonard and Wayne’s study suggests that dogs joined the first humans that made the adventure across the Bering Land Bridge to slowly populate the Americas. Wayne thinks the dogs that made the trip must have provided some excellent service to their human companions or they would not have been brought along. “Dogs must have been useful because they were expensive to keep,” Wayne said. “They didn’t feed on mice; they fed on meat, which was a very guarded resource.”
1. The underlined word “remains” is closed in meaning to ______.
A. leftover food B. animal waste
C. dead bodies D. living environment
2. According to the study described in Paragraph 4, we can learn that ______.
A. ancient dogs entered North America between 1450 and 1675 AD
B. the 11 bones of ancient dogs are not from native American dogs
C. the bones discovered by the gold miners were from North American wolves
D. the bones studied were not from dogs brought into North America by Europeans
3. What can we know from the passage?
A. Native Americans domesticated local wolves into dogs.
B. Scientists discovered some ancient dog remains in 1920s.
C. Latin America’s dogs are different from North America’s in genes.
D. Ancient dogs entered North America across the Bering Land Bridge.
4. The first humans into the New World brought dogs along with them because ______.
A. dogs fed on mice B. dogs were easy to keep
C. dogs helped protect their resources D. dogs could provide excellent service
5.What does the passage mainly talk about ______.
A. the origin of the North American dogs
B. the DNA study of ancient dogs in America
C. the reasons why early people entered America
D. the difference between Asian and American dogs
高三英语阅读理解中等难度题
When people first walked across the Bering Land Bridge thousands of years ago, dogs were by their sides, according to a study published in the journal Science.
Robert Wayne of the University of California, Los Angeles, and Jennifer Leonard of the Smithsonian Institute, used DNA material—some of it unearthed by miners in Alaska—to conclude that today’s domestic dog originated in Asia and accompanied the first humans to the New World about 10,000 to 15,000 years ago. Wayne suggests that man’s best friend may have enabled the tough journey from Asia into North America. “Dogs may have been the reason people made it across the land bridge,” said Wayne. “They can pull things, carry things, defend you from fierce animals, and they’re useful to eat.”
Researchers have agreed that today’s dog is the result of the domestication(驯化) of wolves thousands of years ago. Before this recent study, a common thought about the precise origin of North America’s domestic dog was that Natives domesticated local wolves, the descendents(后代) of which now live with people in Alaska, Canada, and the Lower 48.
Dog remains from a Fairbanks-area gold mine helped the scientists reach their conclusion. Leonard, an evolutionary biologist, collected DNA from 11 bones of ancient dogs that were locked in permafrost(永冻层) until Fairbanks miners uncovered them in the 1920s. The miners donated the preserved bones to the American Museum of Natural History in New York City, where they remained untouched for more than 70 years. After borrowing the bones from the museum, Leonard and her colleagues used radiocarbon techniques to find the age of the Alaska dogs. They found the dogs all lived between the years of 1450 and 1675 A.D., before Vitus Bering and Aleksey Chirikov who were the first known Europeans to view Alaska in 1741. The bones of dogs that wandered the Fairbanks area centuries ago should therefore be the remains of “pure native American dogs,” Leonard said. The DNA of the Fairbanks dogs would also expose whether they were the descendents of wolves from North America.
Along with the Fairbanks samples, the researchers collected DNA from bones of 37 dog specimens(标本) from Mexico, Peru, and Bolivia that existed before the arrival of Columbus. In the case of both the Alaska dogs and the dogs from Latin America, the researchers found that they shared the most genetic material with gray wolves of Europe and Asia. This supports the idea of domestic dogs entering the New World with the first human explorers who wandered east over the land bridge.
Leonard and Wayne’s study suggests that dogs joined the first humans that made the adventure across the Bering Land Bridge to slowly populate the Americas. Wayne thinks the dogs that made the trip must have provided some excellent service to their human companions or they would not have been brought along. “Dogs must have been useful because they were expensive to keep,” Wayne said. “They didn’t feed on mice; they fed on meat, which was a very guarded resource.”
1. The underlined word “remains” is closed in meaning to ______.
A. leftover food B. animal waste
C. dead bodies D. living environment
2. According to the study described in Paragraph 4, we can learn that ______.
A. ancient dogs entered North America between 1450 and 1675 AD
B. the 11 bones of ancient dogs are not from native American dogs
C. the bones discovered by the gold miners were from North American wolves
D. the bones studied were not from dogs brought into North America by Europeans
3. What can we know from the passage?
A. Native Americans domesticated local wolves into dogs.
B. Scientists discovered some ancient dog remains in 1920s.
C. Latin America’s dogs are different from North America’s in genes.
D. Ancient dogs entered North America across the Bering Land Bridge.
4. The first humans into the New World brought dogs along with them because ______.
A. dogs fed on mice B. dogs were easy to keep
C. dogs helped protect their resources D. dogs could provide excellent service
5.What does the passage mainly talk about ______.
A. the origin of the North American dogs
B. the DNA study of ancient dogs in America
C. the reasons why early people entered America
D. the difference between Asian and American dogs
高三英语阅读理解中等难度题查看答案及解析
Across the bridge and _______a vast carpet of green land stands the King’s college, the largest and most beautiful building in Cambridge.
A.beyond B.beneath C.along D.off
高三英语单项填空简单题查看答案及解析
Across the Yangtze River ______ more than one bridge, the Nanjing Changjiang Bridge being the first one.
A.lay | B.lie | C.lies | D.laid |
高三英语单项填空困难题查看答案及解析
Across the Yangtze River _____ more than one bridge, the Nanjing Changjiang Bridge being the first one.
A. lay B. lie
C. lies D. laid
高三英语单项填空中等难度题查看答案及解析
The Golden Gate Bridge, the first sight for many people arriving in the United States by ship, is a well-recognized landmark, which spans(横跨) the Golden Gate Strait.
The idea for a bridge across the strait had been around for many years, but it was not easy to get the project started. The construction of the bridge finally began in 1933. The construction work set new standards for safety----workers were among the first required to wear hard hats, and an innovative(革新的) safety net saved the lives of nineteen men while the bridge was built. The Golden Gate Bridge was completed in 1937, which was finished ahead of schedule.
Joseph Strauss was the chief engineer in charge of the bridge project. However, he had little experience with the construction of suspension(悬浮)bridges. For this reason, other engineers, architects, and designers made great contributions to the design and construction of the bridge. For example, the bridge owes its art style and unique orange color to the architects Irving and Gertrude Morrow. Charles Alton Ellis was the main engineer on the project and did much of the technical work necessary to build the bridge.
Today, the Golden Gate Bridge has a main span of 4,200 feet and a total length of 8,981 feet, making it one of the longest bridges in the world. The bridge is 90 feet wide, and its span is 220 feet above the water. The towers supporting the huge cables (巨缆) rise 746 feet above the waters of the Golden Gate Strait, making them 191 feet taller than the Washington Monument. About 40 million cars cross the bridge every year. There are foghorns(雾角)to let passing ships know where the bridge is, and aircraft beacons(信号灯)on the tops of the towers to stop planes from crashing into them.
1.The purpose of the passage is to _______.
A. describe the construction work of the Golden Gate Bridge
B. introduce the Golden Gate Bridge
C. tell us the history of the Golden Gate Bridge
D. introduce the engineers in charge of the Golden Gate Bridge
2.Safety innovations during the construction of the bridge included ________.
A. hardhats and a safety net B. aircraft beacons
C. foghorns D. all of the above
3. It can be inferred from the passage that _______.
A. Joseph Strauss was skilled in the construction of suspension bridges
B. it took the construction workers three years to build the Golden Gate Bridge
C. about 100 thousand cars cross the Golden Gate Bridge every day
D. the Golden Gate Bridge is the longest bridge in the world
4.The underlined word “them” in Paragraph 4 refers to ________.
A. towers B. cables C. waters D. bridges
高三英语阅读理解中等难度题查看答案及解析
Last weekend, I was walking across the village green(草坪) when I saw an elderly gentleman on the bench, just overlooking the duck pond. I thought he looked a bit forlorn(被遗弃的) so I went over and sat next to him.
After a few 36 about how nice the weather was and how there were a lot of ducks in the pond today, he told me how he used to come with his wife and watch the children feed the ducks with their mums. They didn't have any 37 of their own..So they cherished being together even more.
He explained he had been married for 54 years 38 his wife died and how much he missed 39 all the little things with her, like a beautiful sunset. He now lives in a care home. I remarked at how wonderful it must've been to have been married for so long and to have so many happy memories. He took out a large 40 and wiped his eyes and said he had one regret that in all that time he 41 told her how much he really loved her.
He showed me a photograph of them when they were young. The photo was taken more than 50 years ago. He couldn't believe how the time had 42 . I tried to comfort him by explaining that his wife would be still 43 over him and he could talk to her 44 he wants and that she knows how much he loved her because she can see into his heart.
The old man tried to 45 for blurting out his life story but I hushed him and said how privileged I felt he could talk to me and how much it meant to me.
The 46 I learned from this chance encounter is that we must tell the ones close to us how much we love and care for them and not take them for granted.
Don't 47 your kind acts until tomorrow; do them today because time flies.
1.A. discussionB. comments C. quarrels D. communication
2.A. children B. ducks C. pond D. home
3.A. before B. when C. after D. unless
4.A. doing B. carrying C. sharing D. buying
5.A. paper B. rubber C. brush D. handkerchief
6.A. never B. often C. sometimes D. constantly
7.A. passed on B. passed awayC. passed by D. passed off
8.A. watching B. looking C. seeing D. observing
9.A. every timeB. any time C. some time D. the time
10.A. blame B. cry C. regret D. apologize
11.A. thing B. class C. lesson D. knowledge
12.A. put up B. put down C. put away D. put off
高三英语完型填空简单题查看答案及解析
After graduation went to Nigeria but when I first set foot on strange land,I didn’t Know what the future had in store for me.
A. the;/ B. the;the C. /; a D. the;a
高三英语单项填空中等难度题查看答案及解析
On June 15th,2012,millions of people watched as 33yearold Nik Wallenda walked across one of the world's greatest waterfalls on a tightrope(钢丝).What made the 25-minute walk that was televised live and watched by over 13 million people worldwide even more amazing,is that it was done over the Niagara Falls-An action that had never been attempted before.
Even though Nik was wearing a harness(保护带),a safety measure provided by ABC,the television network that broadcast the event,his action to keep his balance against the strong winds made for some heart-stopping(令人担忧的) moments for the audience.
Nik,however,never slowed down for even one moment.Wearing special shoes made by his mother,he remained totally focused on the job at hand.It was only when he got to the last stretch near Canada's Table Rock that he knelt down on one knee and finally broke into a smile.Waving and blowing kisses to the cheering audience,he knew he had accomplished a great task,which most people had thought impossible.
While he described the whole experience as peaceful and relaxing,Nik said his biggest challenges came from a totally unexpected source-his 40 pound balancing pole.The balancing pole was so heavy that he could hardly carry it on the tightrope.
One would think that now that Nik has realized his lifelong dream he would be ready to hang up his “balancing pole”.However,the adventurer who already has seven Guinness World Records under his belt,is just getting started-Next up? A 5,000-foot tightrope walk across the Grand Canyon.While the one across the Niagara Falls took years of planning because he had to convince the US and Canadian officials,this one should happen in the very near future.That's because,the Florida resident has already been granted(授予) a permit by the Canyon officials.
1.Why did so many people fix their attention on the event?
A.Because it was done by Nik Wallenda.
B.Because nobody had done it there before.
C.Because it was broadcast live by ABC.
D.Because it was impossible to do the event.
2.What made the audience hold their breath during Nik's performance?
A.How Nik managed to cross the Niagara Falls with safety measure.
B.What Nik would do when he lost his balance on the tightrope.
C.How Nik kept his balance against the strong winds.
D.How long Nik will take to finish the event.
3.What was the greatest difficulty for him to face in Nik view?
A.The supplied tightrope. B.The safety belt.
C.The balancing pole. D.The audience's noise.
4.What does the last paragraph mainly talk about?
A.Nik will go on with his dream.
B.Nik's life dream is changing.
C.Permission of governments is important.
D.The Grand Canyon is a dream for Nik.
高三英语阅读理解中等难度题查看答案及解析
On June 15th,2012,millions of people watched as 33yearold Nik Wallenda walked across one of the world's greatest waterfalls on a tightrope(钢丝).What made the 25-minute walk that was televised live and watched by over 13 million people worldwide even more amazing,is that it was done over the Niagara Falls-An action that had never been attempted before.
Even though Nik was wearing a harness(保护带),a safety measure provided by ABC,the television network that broadcast the event,his action to keep his balance against the strong winds made for some heart-stopping(令人担忧的) moments for the audience.
Nik,however,never slowed down for even one moment.Wearing special shoes made by his mother,he remained totally focused on the job at hand.It was only when he got to the last stretch near Canada's Table Rock that he knelt down on one knee and finally broke into a smile.Waving and blowing kisses to the cheering audience,he knew he had accomplished a great task,which most people had thought impossible.
While he described the whole experience as peaceful and relaxing,Nik said his biggest challenges came from a totally unexpected source-his 40 pound balancing pole.The balancing pole was so heavy that he could hardly carry it on the tightrope.
One would think that now that Nik has realized his lifelong dream he would be ready to hang up his “balancing pole”.However,the adventurer who already has seven Guinness World Records under his belt,is just getting started-Next up? A 5,000-foot tightrope walk across the Grand Canyon.While the one across the Niagara Falls took years of planning because he had to convince the US and Canadian officials,this one should happen in the very near future.That's because,the Florida resident has already been granted(授予) a permit by the Canyon officials.
1.Why did so many people fix their attention on the event?
A.Because it was done by Nik Wallenda.
B.Because nobody had done it there before.
C.Because it was broadcast live by ABC.
D.Because it was impossible to do the event.
2.What made the audience hold their breath during Nik's performance?
A.How Nik managed to cross the Niagara Falls with safety measure.
B.What Nik would do when he lost his balance on the tightrope.
C.How Nik kept his balance against the strong winds.
D.How long Nik will take to finish the event.
3.What was the greatest difficulty for him to face in Nik view?
A.The supplied tightrope.
B.The safety belt.
C.The balancing pole.
D.The audience's noise.
4.What does the last paragraph mainly talk about?
A.Nik will go on with his dream.
B.Nik's life dream is changing.
C.Permission of governments is important.
D.The Grand Canyon is a dream for Nik.
高三英语阅读理解中等难度题查看答案及解析
On June 15th,2012,millions of people watched as 33yearold Nik Wallenda walked across one of the world's greatest waterfalls on a tightrope(钢丝).What made the 25-minute walk that was televised live and watched by over 13 million people worldwide even more amazing,is that it was done over the Niagara Falls-An action that had never been attempted before.
Even though Nik was wearing a harness(保护带),a safety measure provided by ABC,the television network that broadcast the event,his action to keep his balance against the strong winds made for some heart-stopping(令人担忧的) moments for the audience.
Nik,however,never slowed down for even one moment.Wearing special shoes made by his mother,he remained totally focused on the job at hand.It was only when he got to the last stretch near Canada's Table Rock that he knelt down on one knee and finally broke into a smile.Waving and blowing kisses to the cheering audience,he knew he had accomplished a great task,which most people had thought impossible.
While he described the whole experience as peaceful and relaxing,Nik said his biggest challenges came from a totally unexpected source-his 40 pound balancing pole.The balancing pole was so heavy that he could hardly carry it on the tightrope.
One would think that now that Nik has realized his lifelong dream he would be ready to hang up his “balancing pole”.However,the adventurer who already has seven Guinness World Records under his belt,is just getting started-Next up? A 5,000-foot tightrope walk across the Grand Canyon.While the one across the Niagara Falls took years of planning because he had to convince the US and Canadian officials,this one should happen in the very near future.That's because,the Florida resident has already been granted(授予) a permit by the Canyon officials.
1.Why did so many people fix their attention on the event?
A.Because it was done by Nik Wallenda.
B.Because nobody had done it there before.
C.Because it was broadcast live by ABC.
D.Because it was impossible to do the event.
2.What made the audience hold their breath during Nik's performance?
A.How Nik managed to cross the Niagara Falls with safety measure.
B.What Nik would do when he lost his balance on the tightrope.
C.How Nik kept his balance against the strong winds.
D.How long Nik will take to finish the event.
3.What was the greatest difficulty for him to face in Nik view?
A.The supplied tightrope.
B.The safety belt.
C.The balancing pole.
D.The audience's noise.
4.What does the last paragraph mainly talk about?
A.Nik will go on with his dream.
B.Nik's life dream is changing.
C.Permission of governments is important.
D.The Grand Canyon is a dream for Nik.
高三英语阅读理解中等难度题查看答案及解析