37. Questions 36 to 40 are based on the following passage.Some people have said aging is more a slide into forgetfulness than a journey towards wisdom.However， a growing body of research suggests that late-in-life learning is possible.In reality， education does an aging brain good.Throughout life， people’s brains constantly renovate themselves.In the late 1960s， British brain scientist Geoffrey Raisman spied growth in damaged brain regions of rats through an electron microscope; their brains were forging new connections.This meant brains may change every time a person learns something new.Of course， that doesn’t mean the brain isn’t affected by the effects of time.Just as height usually declines over the years， so does brain volume: Humans lose about 4 percent every decade starting in their 40s.But that reduction doesn’t necessarily make people think slower; as long as we are alive and functioning， we can alter our brains with new information and experiences.In fact， scientists now suspect accumulating novel experiences， facts， and skills can keep people’s minds more flexible.New pathways can strengthen our ever-changing mental structure， even as the brain shrinks.Conventional fixes like word puzzles and brain-training apps can contribute to mental durability.Even something as simple as taking a different route to the grocery store or going somewhere new on vacation can keep the brain healthy.A desire for new life challenges can further boost brainpower.Research about aging adults who take on new enterprises shows improved function and memory as well as a reduced risk of mental disease.Openness—a characteristic defined by curiosity and a desire for knowledge—may also help folks pass brain tests.Some folks are born with this take-in-the world attitude， but those who aren’t as genetically gifted aren’t necessarily out of luck.While genes can encourage an interest in doing new things， a 2012 study in the journal Psychology and Aging found completing reasoning tasks like puzzles and number games can enhance that desire for novel experiences， which can， in turn， refresh the brain.That’s why brain scientist Richard Kennedy says “It’s not that old dogs can’t learn new tricks.It’s that maybe old dogs don’t realize why they should.”What can we conclude from Geoffrey Raisman’s finding?

2. Passage Thirty-ThreeWe all know that DNA has the ability to identify individuals but， because it is inherited， there are also regions of the DNA strand which can relate an individual to his or her family (immediate and extended)， tribal group and even an entire population.Molecular Genealogy (宗谱学)can use this unique identification provided by the genetic markers to link people together into family trees.Pedigrees (家谱)based on such genetic markers can mean a breakthrough for family trees where information is incomplete or missing due to adoption， illegitimacy or lack of records.There are many communities and populations which have lost precious records due to tragic events such as the fire in the Irish courts during Civil War in 1921 or American slaves for whom many records were never kept in the first place.The main objective of the Molecular Genealogy Research Group is to build a database containing over 100，000 DNA samples from individuals all over the world.These individuals will have provided a pedigree chart of at least four generations and a small blood sample.Once the database has enough samples to represent the world genetic make-up， it will eventually help in solving many issues regarding genealogies that could not be done by relying only on traditional written records.Theoretically， any individual will someday be able to trace his or her family origins through this database.In the meantime， as the database is being created， molecular genealogy can already verify possible or suspected relationships between individuals.“For example， if two men sharing the same last name believe that they are related， but no written record proves this relationship， we can verify this possibility by collecting a sample of DNA from both and looking for common markers (in this case we can look primarily at the Y chromosome (染色体)，” explains Ugo Perego， a member of the BYU Molecular Genealogy research team.The possible research of family trees is based on the fact that ().

1. Passage Thirty-ThreeWe all know that DNA has the ability to identify individuals but， because it is inherited， there are also regions of the DNA strand which can relate an individual to his or her family (immediate and extended)， tribal group and even an entire population.Molecular Genealogy (宗谱学)can use this unique identification provided by the genetic markers to link people together into family trees.Pedigrees (家谱)based on such genetic markers can mean a breakthrough for family trees where information is incomplete or missing due to adoption， illegitimacy or lack of records.There are many communities and populations which have lost precious records due to tragic events such as the fire in the Irish courts during Civil War in 1921 or American slaves for whom many records were never kept in the first place.The main objective of the Molecular Genealogy Research Group is to build a database containing over 100，000 DNA samples from individuals all over the world.These individuals will have provided a pedigree chart of at least four generations and a small blood sample.Once the database has enough samples to represent the world genetic make-up， it will eventually help in solving many issues regarding genealogies that could not be done by relying only on traditional written records.Theoretically， any individual will someday be able to trace his or her family origins through this database.In the meantime， as the database is being created， molecular genealogy can already verify possible or suspected relationships between individuals.“For example， if two men sharing the same last name believe that they are related， but no written record proves this relationship， we can verify this possibility by collecting a sample of DNA from both and looking for common markers (in this case we can look primarily at the Y chromosome (染色体)，” explains Ugo Perego， a member of the BYU Molecular Genealogy research team.People in a large area may possess the same DNA thread because ().

5. Passage Thirty-TwoHave you ever heard of a pawpaw (木瓜)? If not， do not feel bad.Many Americans do not know of the fruit， although it is native to the U.S.Once， however， it was one of the most popular fruits in North America.Happily， those who love the pawpaw are trying to return it to its former position in American foods.A pawpaw is a tropical fruit that used to be grown along the East Coast from New York to Florida and all over the eastern U.S.At one time， it could be found as far west as Nebraska.The pawpaw was an important food for Native Americans and even early European settlers.Pawpaws reportedly were a favorite treat of George Washington， the first U.S.president， who especially liked them cold.Thomas Jefferson， the third U.S.president， was also a fan of the fruit.He planted pawpaws at his home in Virginia.He also sent pawpaw seeds to his friends in France.American explorers Lewis and Clark wrote in their journals about the pawpaw.The pawpaw is difficult to be sold commercially.The fruit requires a very special environment—low， wet areas that sometimes flood.It has a very short harvest season， from two to three weeks in September and October.In addition， the fruit is good to eat for only two to three days after harvesting.This makes it hard to sell anywhere distant from the pawpaw tree it comes from.Planters are again growing pawpaw trees and harvesting the fruit.In several states farmers have organized “pawpaw festivals” to reintroduce people to food.At such a festival in Maryland recently， farmers displayed different products made with pawpaws， like pawpaw jams， pies， ice-cream and beer.Pawpaw festivals are organized in some states ().

4. Passage Thirty-TwoHave you ever heard of a pawpaw (木瓜)? If not， do not feel bad.Many Americans do not know of the fruit， although it is native to the U.S.Once， however， it was one of the most popular fruits in North America.Happily， those who love the pawpaw are trying to return it to its former position in American foods.A pawpaw is a tropical fruit that used to be grown along the East Coast from New York to Florida and all over the eastern U.S.At one time， it could be found as far west as Nebraska.The pawpaw was an important food for Native Americans and even early European settlers.Pawpaws reportedly were a favorite treat of George Washington， the first U.S.president， who especially liked them cold.Thomas Jefferson， the third U.S.president， was also a fan of the fruit.He planted pawpaws at his home in Virginia.He also sent pawpaw seeds to his friends in France.American explorers Lewis and Clark wrote in their journals about the pawpaw.The pawpaw is difficult to be sold commercially.The fruit requires a very special environment—low， wet areas that sometimes flood.It has a very short harvest season， from two to three weeks in September and October.In addition， the fruit is good to eat for only two to three days after harvesting.This makes it hard to sell anywhere distant from the pawpaw tree it comes from.Planters are again growing pawpaw trees and harvesting the fruit.In several states farmers have organized “pawpaw festivals” to reintroduce people to food.At such a festival in Maryland recently， farmers displayed different products made with pawpaws， like pawpaw jams， pies， ice-cream and beer.It is difficult to sell the pawpaw on a large scale for the following reasons EXCEPT that the fruit ().

3. Passage Thirty-TwoHave you ever heard of a pawpaw (木瓜)? If not， do not feel bad.Many Americans do not know of the fruit， although it is native to the U.S.Once， however， it was one of the most popular fruits in North America.Happily， those who love the pawpaw are trying to return it to its former position in American foods.A pawpaw is a tropical fruit that used to be grown along the East Coast from New York to Florida and all over the eastern U.S.At one time， it could be found as far west as Nebraska.The pawpaw was an important food for Native Americans and even early European settlers.Pawpaws reportedly were a favorite treat of George Washington， the first U.S.president， who especially liked them cold.Thomas Jefferson， the third U.S.president， was also a fan of the fruit.He planted pawpaws at his home in Virginia.He also sent pawpaw seeds to his friends in France.American explorers Lewis and Clark wrote in their journals about the pawpaw.The pawpaw is difficult to be sold commercially.The fruit requires a very special environment—low， wet areas that sometimes flood.It has a very short harvest season， from two to three weeks in September and October.In addition， the fruit is good to eat for only two to three days after harvesting.This makes it hard to sell anywhere distant from the pawpaw tree it comes from.Planters are again growing pawpaw trees and harvesting the fruit.In several states farmers have organized “pawpaw festivals” to reintroduce people to food.At such a festival in Maryland recently， farmers displayed different products made with pawpaws， like pawpaw jams， pies， ice-cream and beer.George Washington and Thomas Jefferson are mentioned in paragraph 3 as ().

2. Passage Thirty-TwoHave you ever heard of a pawpaw (木瓜)? If not， do not feel bad.Many Americans do not know of the fruit， although it is native to the U.S.Once， however， it was one of the most popular fruits in North America.Happily， those who love the pawpaw are trying to return it to its former position in American foods.A pawpaw is a tropical fruit that used to be grown along the East Coast from New York to Florida and all over the eastern U.S.At one time， it could be found as far west as Nebraska.The pawpaw was an important food for Native Americans and even early European settlers.Pawpaws reportedly were a favorite treat of George Washington， the first U.S.president， who especially liked them cold.Thomas Jefferson， the third U.S.president， was also a fan of the fruit.He planted pawpaws at his home in Virginia.He also sent pawpaw seeds to his friends in France.American explorers Lewis and Clark wrote in their journals about the pawpaw.The pawpaw is difficult to be sold commercially.The fruit requires a very special environment—low， wet areas that sometimes flood.It has a very short harvest season， from two to three weeks in September and October.In addition， the fruit is good to eat for only two to three days after harvesting.This makes it hard to sell anywhere distant from the pawpaw tree it comes from.Planters are again growing pawpaw trees and harvesting the fruit.In several states farmers have organized “pawpaw festivals” to reintroduce people to food.At such a festival in Maryland recently， farmers displayed different products made with pawpaws， like pawpaw jams， pies， ice-cream and beer.The pawpaw used to be found mainly ().

1. Passage Thirty-TwoHave you ever heard of a pawpaw (木瓜)? If not， do not feel bad.Many Americans do not know of the fruit， although it is native to the U.S.Once， however， it was one of the most popular fruits in North America.Happily， those who love the pawpaw are trying to return it to its former position in American foods.A pawpaw is a tropical fruit that used to be grown along the East Coast from New York to Florida and all over the eastern U.S.At one time， it could be found as far west as Nebraska.The pawpaw was an important food for Native Americans and even early European settlers.Pawpaws reportedly were a favorite treat of George Washington， the first U.S.president， who especially liked them cold.Thomas Jefferson， the third U.S.president， was also a fan of the fruit.He planted pawpaws at his home in Virginia.He also sent pawpaw seeds to his friends in France.American explorers Lewis and Clark wrote in their journals about the pawpaw.The pawpaw is difficult to be sold commercially.The fruit requires a very special environment—low， wet areas that sometimes flood.It has a very short harvest season， from two to three weeks in September and October.In addition， the fruit is good to eat for only two to three days after harvesting.This makes it hard to sell anywhere distant from the pawpaw tree it comes from.Planters are again growing pawpaw trees and harvesting the fruit.In several states farmers have organized “pawpaw festivals” to reintroduce people to food.At such a festival in Maryland recently， farmers displayed different products made with pawpaws， like pawpaw jams， pies， ice-cream and beer.Many American people do not know that the pawpaw ().

5. Passage Thirty-OneAdam Smith was the first person to see the importance of the division of labor.He gave us an example of the process by which pins were made in England.“One man draws out the wire， another strengthens it， a third cuts it， a fourth points it， and a fifth gives it a head.Just to make the head requires two or three different operations.The work of making pins is divided into about eighteen different operations， which in some factories are all performed by different people， though in others the same man will sometimes perform two or three of them.”Ten men， Smith said， in this way， turned out twelve pounds of pins a day or about 4，800 pins a worker.But if all of them had worked separately and independently without division of labor， they certainly could not have made twenty pins in a day and not even one.There can be no doubt that division of labor is an efficient way of organizing work.Fewer people can make more pins.Adam Smith saw this， but he also took it for granted that division of labor is itself responsible for economic growth and development and it accounts for the difference between expanding economies and those that stand still.But division of labor adds nothing new， it only enables people to produce more of what they already have.According to the writer， which of the following is NOT true?

4. Passage Thirty-OneAdam Smith was the first person to see the importance of the division of labor.He gave us an example of the process by which pins were made in England.“One man draws out the wire， another strengthens it， a third cuts it， a fourth points it， and a fifth gives it a head.Just to make the head requires two or three different operations.The work of making pins is divided into about eighteen different operations， which in some factories are all performed by different people， though in others the same man will sometimes perform two or three of them.”Ten men， Smith said， in this way， turned out twelve pounds of pins a day or about 4，800 pins a worker.But if all of them had worked separately and independently without division of labor， they certainly could not have made twenty pins in a day and not even one.There can be no doubt that division of labor is an efficient way of organizing work.Fewer people can make more pins.Adam Smith saw this， but he also took it for granted that division of labor is itself responsible for economic growth and development and it accounts for the difference between expanding economies and those that stand still.But division of labor adds nothing new， it only enables people to produce more of what they already have.According to the writer， Adam Smith’s mistake was in believing that the division of labor ().

3. Passage Thirty-OneAdam Smith was the first person to see the importance of the division of labor.He gave us an example of the process by which pins were made in England.“One man draws out the wire， another strengthens it， a third cuts it， a fourth points it， and a fifth gives it a head.Just to make the head requires two or three different operations.The work of making pins is divided into about eighteen different operations， which in some factories are all performed by different people， though in others the same man will sometimes perform two or three of them.”Ten men， Smith said， in this way， turned out twelve pounds of pins a day or about 4，800 pins a worker.But if all of them had worked separately and independently without division of labor， they certainly could not have made twenty pins in a day and not even one.There can be no doubt that division of labor is an efficient way of organizing work.Fewer people can make more pins.Adam Smith saw this， but he also took it for granted that division of labor is itself responsible for economic growth and development and it accounts for the difference between expanding economies and those that stand still.But division of labor adds nothing new， it only enables people to produce more of what they already have.Adam Smith mentioned the number 4，800 in order to ().