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 ().

45.She gave us food and clothes and asked for nothing in return， which made us very grateful.

44.The firefighters thought little of their personal safety and as usual rescued the people who were trapped in the fire.

43.The government should come up with a better solution to the problems caused by the high price of petrol.

42.We should take an active part in community service， which can enrich our life.

41.A hobby is something that you never get tired of—the more time you devote to it， the more fun you will have.

40. 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 is the finding of the 2012 study in the journal Psychology and Aging?

39. 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 does the author say can contribute to the improvement of brain function?

38. 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 is one thing that helps maintain the health of our brain even as it shrinks?

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?

36. 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 do some people think of aging adults?