单选题Although many people would not believe it, the mosquito is actually the most dangerous animal in Africa. While the bite of the black mamba is invariably lethal when untreated, this dreaded snake kills only a few dozen people per year. Hippopotami, with

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Craig Rogers was sitting on his surfboard, scanning（审视）the distance for his next wave, when his board suddenly stopped moving._________(46)"I could have touched its eye with my elbow（肘部）,"says Craig. The shark had surfaced so quietly that he hadn't heard a thing.
In his horror and confusion,he waved his arms and accidentally cut two of his fingers on the shark's teeth.He then slid off the opposite side of his surfboard into the water. Then,with Craig in the water and blood flowing from his fingers,the five-meter-long shark simply swam away,_______(47)
Although sharks are often categorized as killers that hunt and eat as many humans as they can, this is actually inaccurate.Sharks very rarely kill humans.A person has a greater chance of being struck by lightning or drowning（淹死）in a bath than of being killed by a shark. Only 74 people have been reported killed by great whites in the last century.But great white sharks can reach six meters in length and weigh 2,200 kilograms or more.With frightening jaws that can hold up to
3,000 teeth arranged in several rows,they could very easily kill and eat a helpless human in the water.________(48)Shark researchers are trying to comprehend the reasons that allow people to escape without being eaten.
The most common explanation is that great whites don't see well._________(49)There is reason to doubt this,however. Recent information shows that great whites can actually see very well. Also,when attacking seals,great whites shoot up to the surface and bite with great force.When approaching humans,however,_________(50)They soon discover that humans are not a high一fat meal."They spit us out because we're too bony,"says Aidan Martin,director of Reef Quest Center for Shark Research.
Shark researchers like Martin hypothesize that great whites are actually curious animals that like to investigate things.It's possible that they use their bite not only to kill and eat,but also to gather information.Although such an experience is unlucky for people like Craig Rogers,when sharks bite surfboards or other objects or people,they are likely just trying to learn what they are.

_________（50）
A:disappearing into the water below.
B:Why is it,then,that most people survive attacks by great whites?
C:they most often move in slowly and bite less hard.
D:There is reason to doubt that great whites see well enough to attack humans.
E:It has been thought that they mistake people for the seals or sea lions which make up a large part of their diet.
F:He looked down and was terrified to see a great white shark biting the front of his board.

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Eastern Quakes can Trigger Big Shakes

In the first week of November 2011,people in central Oklahoma experienced more than two dozen earth-
quakes.The largest,a magnitude（量）5.6 quake,shook thousands of fans in a college football stadium,
caused cracks in a few buildings and scared many people who had never felt a quake before.Oklahoma is not
an area of the country famous for its quakes.If you watch the news on TV,you will see reports about all sorts
of natural disasters.But the most dangerous type of natural disaster,and also the most unpredictable,is the
earthquake.
Researchers at the US Geological Survey(USGS)estimate that several million earthquakes occur globally
each year. That may sound scary,but people don't feel many of them because they happen in remote and
unpopulated regions.Many quakes happen under the ocean,and others have a very small magnitude.
Scientists know about small,remote quakes only because of very sensitive electronic devices called seis-
mometers（地震仪）.These devices detect and measure the size of ground vibrations（震颤）produced by
earthquakes.Altogether,USGS researchers use seismometers to identify and locate about 20,000 earthquakes
each year.
Although earthquakes can happen anywhere in the world,really big quakes occur only in certain areas.
The largest ones register a magnitude 8 or higher and happen,on average,only once each year. Such big
ones typically occur along the edges of Earth ' s tectonic plates（构造板块）.
Tectonic plates are huge pieces of Earth ' s crust（外壳）,sometimes many kilometers thick. Often,
edges of these plates temporarily lock together. When plates push and scrape（擦）past each other earthquakes
occur. On average,tectonic plates move very slowly一about the same speed as your fingernails grow.
But sometimes earthquakes rumble（轰轰作响）through portions of the landscape far from a plate ' s
edges.Although less expected,these"mid-plate"small earthquakes can do substantial damage.Some of the
biggest known examples hit the eastern half of the United States two centuries ago.Today,scientists are still
puzzling over why the quakes occurred and when similar ones might occur.

The earthquake is the most unpredictable natural disaster.
A:Right
B:Wrong
C:Not mentioned

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Prolonging Human Life

1.Prolonging human life has increased the size of the human population.Many people alive today would have died of childhood diseases if they had been born 100 years ago.Because more people live longer,there are more people around at any given time.In fact,it is a decrease in death rates,not an increase in birthrates,that has led to the population explosion.
2.Prolonging human life has also increased the dependency load.In all societies,people who are disabled or too young or too old to work are dependent on the rest of society to provide for them. In hunting and gathering cultures,old people who could not keep up might be left behind to die.In times of famine,infants might be allowed to die because they could not survive if their parents starved,whereas if the parents survived they could have another child.
3.In most contemporary societies,people feel a moral obligation to keep people alive whether they can work or not. We have a great many people today who live past the age at which they want to work or are able to work.We also have rules which require people to retire at a certain age.Unless these people were able to save money for their retirement,somebody else must support them.In the United States many retired people live on social security checks which are so little that they must live in near poverty. Older people have more illness than young or middle-aged people.Unless they have wealth or private or government insurance,they must often"go on welfare"if they have a serious illness.
4.When older people become senile or too weak and ill to care for themselves,they create grave problems for their families.In the past and in some traditional cultures,they would be cared for at home until they died.Today,with most members of a household working or in school,there is often no one at home who can care for a sick or weak person.To meet this need,a great many nursing homes and convalescent hospitals have been built. These are often profit-making organizations, although some are sponsored by religious and other nonprofit groups.While a few of these institutions are good,most of them are simply"dumping grounds"for the dying in which"care"is given by poorly paid,overworked,and under-skilled personnel.

Many people would have died of_______if they had been born 100 years ago.
A:too weak and ill
B:hunting and gathering cultures
C:childhood diseases
D:no one at home
E:epidemic diseases
F: traditional cultures

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Eastern Quakes can Trigger Big Shakes

In the first week of November 2011,people in central Oklahoma experienced more than two dozen earth-
quakes.The largest,a magnitude（量）5.6 quake,shook thousands of fans in a college football stadium,
caused cracks in a few buildings and scared many people who had never felt a quake before.Oklahoma is not
an area of the country famous for its quakes.If you watch the news on TV,you will see reports about all sorts
of natural disasters.But the most dangerous type of natural disaster,and also the most unpredictable,is the
earthquake.
Researchers at the US Geological Survey(USGS)estimate that several million earthquakes occur globally
each year. That may sound scary,but people don't feel many of them because they happen in remote and
unpopulated regions.Many quakes happen under the ocean,and others have a very small magnitude.
Scientists know about small,remote quakes only because of very sensitive electronic devices called seis-
mometers（地震仪）.These devices detect and measure the size of ground vibrations（震颤）produced by
earthquakes.Altogether,USGS researchers use seismometers to identify and locate about 20,000 earthquakes
each year.
Although earthquakes can happen anywhere in the world,really big quakes occur only in certain areas.
The largest ones register a magnitude 8 or higher and happen,on average,only once each year. Such big
ones typically occur along the edges of Earth ' s tectonic plates（构造板块）.
Tectonic plates are huge pieces of Earth ' s crust（外壳）,sometimes many kilometers thick. Often,
edges of these plates temporarily lock together. When plates push and scrape（擦）past each other earthquakes
occur. On average,tectonic plates move very slowly一about the same speed as your fingernails grow.
But sometimes earthquakes rumble（轰轰作响）through portions of the landscape far from a plate ' s
edges.Although less expected,these"mid-plate"small earthquakes can do substantial damage.Some of the
biggest known examples hit the eastern half of the United States two centuries ago.Today,scientists are still
puzzling over why the quakes occurred and when similar ones might occur.

Seismometers can identify and locate most of the earthquakes in China.
A:Right
B:Wrong
C:Not mentioned

共用题干
Eastern Quakes can Trigger Big Shakes

In the first week of November 2011,people in central Oklahoma experienced more than two dozen earth-
quakes.The largest,a magnitude（量）5.6 quake,shook thousands of fans in a college football stadium,
caused cracks in a few buildings and scared many people who had never felt a quake before.Oklahoma is not
an area of the country famous for its quakes.If you watch the news on TV,you will see reports about all sorts
of natural disasters.But the most dangerous type of natural disaster,and also the most unpredictable,is the
earthquake.
Researchers at the US Geological Survey(USGS)estimate that several million earthquakes occur globally
each year. That may sound scary,but people don't feel many of them because they happen in remote and
unpopulated regions.Many quakes happen under the ocean,and others have a very small magnitude.
Scientists know about small,remote quakes only because of very sensitive electronic devices called seis-
mometers（地震仪）.These devices detect and measure the size of ground vibrations（震颤）produced by
earthquakes.Altogether,USGS researchers use seismometers to identify and locate about 20,000 earthquakes
each year.
Although earthquakes can happen anywhere in the world,really big quakes occur only in certain areas.
The largest ones register a magnitude 8 or higher and happen,on average,only once each year. Such big
ones typically occur along the edges of Earth ' s tectonic plates（构造板块）.
Tectonic plates are huge pieces of Earth ' s crust（外壳）,sometimes many kilometers thick. Often,
edges of these plates temporarily lock together. When plates push and scrape（擦）past each other earthquakes
occur. On average,tectonic plates move very slowly一about the same speed as your fingernails grow.
But sometimes earthquakes rumble（轰轰作响）through portions of the landscape far from a plate ' s
edges.Although less expected,these"mid-plate"small earthquakes can do substantial damage.Some of the
biggest known examples hit the eastern half of the United States two centuries ago.Today,scientists are still
puzzling over why the quakes occurred and when similar ones might occur.

Few earthquakes happen without people'S awareness.
A:Right
B:Wrong
C:Not mentioned

While some office jobs would seem boring to many people,there are quite a few jobs that are stimulating,exciting and satisfying.

A:hostile
B:tedious
C:fantastic
D:courageous

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Prolonging Human Life
Prolonging human life has increased the size of the human population. Many people alive
today would have died of childhood diseases if they had been born 100 years ago.Because
more people live longer,there are more people around at any given time. In fact,it is a decrease in death rates,not an increase in birthrates,that has led to the population explosion.
Prolonging human life has also increased the dependency load. In all societies,people who are disabled or too young or too old to work are dependent on the rest of society to provide for them. In hunting and gathering cultures,old people who could not keep up might be left behind to die. In times of famine,infants might be allowed to die because they could not survive if their parents starved,whereas if the parents survived they could have another child. In most contemporary societies,people feel a moral obligation to keep people alive whether they can work or not. We have a great many people today who live past the age at which they want to work or are able to work;we also have rules which require people to retire at a certain age. Unless these people were able to save money for their retirement,some-body else must support them. In the United States many retired people live on social security checks which are so little that they must live in near poverty. Older people have more illness than young or middle-aged people;unless they have wealth or private or government insur-ance,they must often“go on welfare” if they have a serious illness.
When older people become senile or too weak and ill to care for themselves,they create grave problems for their families. In the past and in some traditional cultures,they would be cared for at home until they died. Today,with most members of a household working or in school,there is often no one at home who can care for a sick or weak person. To meet this need,a great many nursing homes and convalescent hospitals have been built.These are of-ten profit-making organizations,although some are sponsored by religious and other nonprofit groups.While a few of these institutions are good,most of them are simply“dumping grounds”for the dying in which“care”is given by poorly paid,overworked,and under-skilled personnel.

Which of the following best describes the writer's attitude toward most of the nursing homes,and convalescent hospitals?
A: Sympathetic.
B: Unfriendly.
C: Optimistic.
D: Critical.

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Prolonging Human Life

1.Prolonging human life has increased the size of the human population.Many people alive today would have died of childhood diseases if they had been born 100 years ago.Because more people live longer,there are more people around at any given time.In fact,it is a decrease in death rates,not an increase in birthrates,that has led to the population explosion.
2.Prolonging human life has also increased the dependency load.In all societies,people who are disabled or too young or too old to work are dependent on the rest of society to provide for them. In hunting and gathering cultures,old people who could not keep up might be left behind to die.In times of famine,infants might be allowed to die because they could not survive if their parents starved,whereas if the parents survived they could have another child.
3.In most contemporary societies,people feel a moral obligation to keep people alive whether they can work or not. We have a great many people today who live past the age at which they want to work or are able to work.We also have rules which require people to retire at a certain age.Unless these people were able to save money for their retirement,somebody else must support them.In the United States many retired people live on social security checks which are so little that they must live in near poverty. Older people have more illness than young or middle-aged people.Unless they have wealth or private or government insurance,they must often"go on welfare"if they have a serious illness.
4.When older people become senile or too weak and ill to care for themselves,they create grave problems for their families.In the past and in some traditional cultures,they would be cared for at home until they died.Today,with most members of a household working or in school,there is often no one at home who can care for a sick or weak person.To meet this need,a great many nursing homes and convalescent hospitals have been built. These are often profit-making organizations, although some are sponsored by religious and other nonprofit groups.While a few of these institutions are good,most of them are simply"dumping grounds"for the dying in which"care"is given by poorly paid,overworked,and under-skilled personnel.

When older people become_______to care for themselves,they create grave problems for their families.
A:too weak and ill
B:hunting and gathering cultures
C:childhood diseases
D:no one at home
E:epidemic diseases
F: traditional cultures