During the last glacial period, vast ice sheets covered much of the Northern Hemisphere, and drought and desertification were common. Roughly 20,000 years ago, the Northern Hemisphere began to warm again. The great ice sheets began to thaw and recede, and the deep freeze of the last glacial period ended. In North America, much of the runoff water from the melting ice sheets became trapped behind a ridge of debris deposited at the base of the shrinking glaciers. This formed immense meltwater lakes, the largest of which has been named Lake Agassiz. By 11,000 B.C., Lake Agassiz had expanded to cover almost half a million square kilometers of Canada and the northern United States-an area about the size of the Black Sea. Then, the inevitable happened. The natural dam (barrier) burst and the huge volume of glacial water poured out in an immense, surging flood. This sudden release of the trapped water caused an immediate jump in global sea levels.
Whilst the ice sheets were shrinking, forests expanded again to replace the wide bands of dry grasslands and scrubland. Rivers swelled, and deserts shrank. With the warmer, wetter conditions, lush vegetation proliferated and populations of grazing(plant- eating)mammals increased. Springtime was returning to the planet, and our hunter-gatherer ancestors found the going much easier. East of the Mediterranean Sea, the land flushed with wild wheat, rye, and barley, and with recovering woodland. Here a people known as the Natufians emerged, who appear to have formed the first sedentary(settled) society in the world, even before the development of agriculture. They settled in villages of stone and wood, gathering the wild grains along with fruit and nuts from the woodland, and hunting gazelle. This golden era didn’t last long, however. Around 11,000 B.c. a sharp climatic jolt, lasting over 1,000 years, struck this region and the Northern Hemisphere as a whole. This is known as the Younger Dryas event, and it saw a rapid regression of climate, which over the course of just a few decades returned towards a much colder and drier state. And the cause for this abrupt return to glacial conditions is thought to have been the pouring out of Lake Agassiz.
The sudden drainage of this vast lake placed a lid of freshwater on the northern Atlantic, which temporarily shut down the pattern of ocean circulation. Today, the world’s oceans operate vigorous conveyor belts of cycling waters that transport heat from the equator towards the poles. This is known as the thermohaline circulation, as it is driven by differences in the temperature and salinity(saltiness) of the seawater. Winds blow the warm surface waters from the planet’s middle towards higher latitudes, sustaining the Gulf Stream current, for example, that delivers Caribbean warmth and moisture to Northern Europe. Evaporation along the way turns the seawater more salty, and it also cools on its journey north. Both these effects make the water more dense, so that near the poles it sinks to the ocean floor and returns towards the equator at depth. The sinking of polar water also draws in more water behind it to maintain the current. But the rapid dumping of a huge amount of freshwater into the North Atlantic from the discharge of Lake Agassiz abruptly stalled the effect of salinity on the current’s circulation. The shutting down of the ocean circulation system, which was redistributing heat from the equator, returned much of the Northern Hemisphere to the conditions experienced during the height of the last glacial period.
For the Natufians, the environmental crisis of plunging temperatures and declining rainfall saw their homelands reverting to dry, treeless grasslands of thorny scrubs, and the abundant wild food sources dwindled before their eyes. It seems that at least some of the Natufians responded by abandoning their fledgling sedentary lifestyle and returning to migratory gathering. But some archaeologists believe that this Younger Dryas event spurred others to turn from their hunter-gatherer ways and instead develop agriculture. Rather than roaming farther and farther to collect enough food to survive, they brought seeds home and planted them in the ground-the first step of plant domestication.
1
During the last glacial period, vast ice sheets covered much of the Northern Hemisphere, and drought and desertification were common. Roughly 20,000 years ago, the Northern Hemisphere began to warm again. The great ice sheets began to thaw and recede, and the deep freeze of the last glacial period ended. In North America, much of the runoff water from the melting ice sheets became trapped behind a ridge of debris deposited at the base of the shrinking glaciers. This formed immense meltwater lakes, the largest of which has been named Lake Agassiz. By 11,000 B.C., Lake Agassiz had expanded to cover almost half a million square kilometers of Canada and the northern United States-an area about the size of the Black Sea. Then, the inevitable happened. The natural dam (barrier) burst and the huge volume of glacial water poured out in an immense, surging flood. This sudden release of the trapped water caused an immediate jump in global sea levels.
According to paragraph 1， which of the following caused Lake Agassiz to lose its water?
Factual Information Questions事实信息题
AThe deep freeze of the last glacial period
BA period of drought and desertification
CA bursting of the barrier of debris keeping the water in place
DA sudden warming in the Northern Hemisphere
2
Whilst the ice sheets were shrinking, forests expanded again to replace the wide bands of dry grasslands and scrubland. Rivers swelled, and deserts shrank. With the warmer, wetter conditions, lush vegetation proliferated and populations of grazing(plant- eating)mammals increased. Springtime was returning to the planet, and our hunter-gatherer ancestors found the going much easier. East of the Mediterranean Sea, the land flushed with wild wheat, rye, and barley, and with recovering woodland. Here a people known as the Natufians emerged, who appear to have formed the first sedentary(settled) society in the world, even before the development of agriculture. They settled in villages of stone and wood, gathering the wild grains along with fruit and nuts from the woodland, and hunting gazelle. This golden era didn’t last long, however. Around 11,000 B.c. a sharp climatic jolt, lasting over 1,000 years, struck this region and the Northern Hemisphere as a whole. This is known as the Younger Dryas event, and it saw a rapid regression of climate, which over the course of just a few decades returned towards a much colder and drier state. And the cause for this abrupt return to glacial conditions is thought to have been the pouring out of Lake Agassiz.
Which of the following can be inferred from paragraph 2 about the Natufian people?
Inference Questions推理题
ATheir sedentary lifestyle was made possible by an abundant food supply.
BThey built villages of stone and wood in response to sharp climatic jolts.
CTheir activities contributed to the recovery of woodland east of the Mediterranean Sea.
DThey benefited from the climate that followed the Younger Dryas event.
3
Whilst the ice sheets were shrinking, forests expanded again to replace the wide bands of dry grasslands and scrubland. Rivers swelled, and deserts shrank. With the warmer, wetter conditions, lush vegetation proliferated and populations of grazing(plant- eating)mammals increased. Springtime was returning to the planet, and our hunter-gatherer ancestors found the going much easier. East of the Mediterranean Sea, the land flushed with wild wheat, rye, and barley, and with recovering woodland. Here a people known as the Natufians emerged, who appear to have formed the first sedentary(settled) society in the world, even before the development of agriculture. They settled in villages of stone and wood, gathering the wild grains along with fruit and nuts from the woodland, and hunting gazelle. This golden era didn’t last long, however. Around 11,000 B.c. a sharp climatic jolt, lasting over 1,000 years, struck this region and the Northern Hemisphere as a whole. This is known as the Younger Dryas event, and it saw a rapid regression of climate, which over the course of just a few decades returned towards a much colder and drier state. And the cause for this abrupt return to glacial conditions is thought to have been the pouring out of Lake Agassiz.
According to paragraph 2， all of the following characterized the period BEFORE the Younger Dryas event EXCEPT:
Negative Factual Information Questions否定事实信息题
AIce sheets were decreasing in size.
BForests began growing in places that had previously been dry.
CThe numbers of some plant-eating animals increased.
DPeople were developing agriculture.
4
The sudden drainage of this vast lake placed a lid of freshwater on the northern Atlantic, which temporarily shut down the pattern of ocean circulation. Today, the world’s oceans operate vigorous conveyor belts of cycling waters that transport heat from the equator towards the poles. This is known as the thermohaline circulation, as it is driven by differences in the temperature and salinity(saltiness) of the seawater. Winds blow the warm surface waters from the planet’s middle towards higher latitudes, sustaining the Gulf Stream current, for example, that delivers Caribbean warmth and moisture to Northern Europe. Evaporation along the way turns the seawater more salty, and it also cools on its journey north. Both these effects make the water more dense, so that near the poles it sinks to the ocean floor and returns towards the equator at depth. The sinking of polar water also draws in more water behind it to maintain the current. But the rapid dumping of a huge amount of freshwater into the North Atlantic from the discharge of Lake Agassiz abruptly stalled the effect of salinity on the current’s circulation. The shutting down of the ocean circulation system, which was redistributing heat from the equator, returned much of the Northern Hemisphere to the conditions experienced during the height of the last glacial period.
The word “vigorous”in the passage is closest in meaning to
Vocabulary Questions词汇题
Alarge
Bcontinuous
Cpowerful
Dpredictable
5
The sudden drainage of this vast lake placed a lid of freshwater on the northern Atlantic, which temporarily shut down the pattern of ocean circulation. Today, the world’s oceans operate vigorous conveyor belts of cycling waters that transport heat from the equator towards the poles. This is known as the thermohaline circulation, as it is driven by differences in the temperature and salinity(saltiness) of the seawater. Winds blow the warm surface waters from the planet’s middle towards higher latitudes, sustaining the Gulf Stream current, for example, that delivers Caribbean warmth and moisture to Northern Europe. Evaporation along the way turns the seawater more salty, and it also cools on its journey north. Both these effects make the water more dense, so that near the poles it sinks to the ocean floor and returns towards the equator at depth. The sinking of polar water also draws in more water behind it to maintain the current. But the rapid dumping of a huge amount of freshwater into the North Atlantic from the discharge of Lake Agassiz abruptly stalled the effect of salinity on the current’s circulation. The shutting down of the ocean circulation system, which was redistributing heat from the equator, returned much of the Northern Hemisphere to the conditions experienced during the height of the last glacial period.
According to paragraph 3， which TWO of the following happen to the water in the Gulf Stream current on its way north? To receive credit,you must select TWO answer choices.
Factual Information Questions事实信息题
Select 2 answers
AIts saltiness decreases.
BIts rate of evaporation increases.
CIts temperature decreases.
DIts density increases.
6
The sudden drainage of this vast lake placed a lid of freshwater on the northern Atlantic, which temporarily shut down the pattern of ocean circulation. Today, the world’s oceans operate vigorous conveyor belts of cycling waters that transport heat from the equator towards the poles. This is known as the thermohaline circulation, as it is driven by differences in the temperature and salinity(saltiness) of the seawater. Winds blow the warm surface waters from the planet’s middle towards higher latitudes, sustaining the Gulf Stream current, for example, that delivers Caribbean warmth and moisture to Northern Europe. Evaporation along the way turns the seawater more salty, and it also cools on its journey north. Both these effects make the water more dense, so that near the poles it sinks to the ocean floor and returns towards the equator at depth. The sinking of polar water also draws in more water behind it to maintain the current. But the rapid dumping of a huge amount of freshwater into the North Atlantic from the discharge of Lake Agassiz abruptly stalled the effect of salinity on the current’s circulation. The shutting down of the ocean circulation system, which was redistributing heat from the equator, returned much of the Northern Hemisphere to the conditions experienced during the height of the last glacial period.
According to paragraph 3， the thermohaline circulation system depends on the occurrence of all of the following EXCEPT
Negative Factual Information Questions否定事实信息题
Awinds pushing surface waters from the equator toward higher latitudes
Bthe downward flow of dense water near the poles
Cadditional water being pulled to follow sinking water
Dthe continuous flow of freshwater into the ocean
7
The sudden drainage of this vast lake placed a lid of freshwater on the northern Atlantic, which temporarily shut down the pattern of ocean circulation. Today, the world’s oceans operate vigorous conveyor belts of cycling waters that transport heat from the equator towards the poles. This is known as the thermohaline circulation, as it is driven by differences in the temperature and salinity(saltiness) of the seawater. Winds blow the warm surface waters from the planet’s middle towards higher latitudes, sustaining the Gulf Stream current, for example, that delivers Caribbean warmth and moisture to Northern Europe. Evaporation along the way turns the seawater more salty, and it also cools on its journey north. Both these effects make the water more dense, so that near the poles it sinks to the ocean floor and returns towards the equator at depth. The sinking of polar water also draws in more water behind it to maintain the current. But the rapid dumping of a huge amount of freshwater into the North Atlantic from the discharge of Lake Agassiz abruptly stalled the effect of salinity on the current’s circulation. The shutting down of the ocean circulation system, which was redistributing heat from the equator, returned much of the Northern Hemisphere to the conditions experienced during the height of the last glacial period.
In paragraph 3， why does the author describe how the thermohaline circulation system operates?
Factual Information Questions事实信息题
ATo help explain the effects of the discharge of Lake Agassiz on the climate in the Northern Hemisphere
BTo compare today’s ocean circulation with that of the last glacial period
CTo illustrate how the Gulf Stream current affects circulation in other parts of the ocean
DTo support the idea that the discharge of Lake Agassiz changed the direction of ocean circulation
8
For the Natufians, the environmental crisis of plunging temperatures and declining rainfall saw their homelands reverting to dry, treeless grasslands of thorny scrubs, and the abundant wild food sources dwindled before their eyes. It seems that at least some of the Natufians responded by abandoning their fledgling sedentary lifestyle and returning to migratory gathering. But some archaeologists believe that this Younger Dryas event spurred others to turn from their hunter-gatherer ways and instead develop agriculture. Rather than roaming farther and farther to collect enough food to survive, they brought seeds home and planted them in the ground-the first step of plant domestication.
Paragraph 4 suggests that some Natufians began moving over larger areas than they had before for which of the following reasons?
Inference Questions推理题
AThey were looking for areas that were more suitable to agriculture than the areas where they lived.
BThe treeless grasslands that they depended on for food were shifting farther and farther away from their homelands.
CPlant domestication freed them from the need to collect food and gave them time to explore new areas.
DThe drier climate made it difficult for them to find food in a single area.
9
During the last glacial period, vast ice sheets covered much of the Northern Hemisphere, and drought and desertification were common. Roughly 20,000 years ago, the Northern Hemisphere began to warm again. The great ice sheets began to thaw and recede, and the deep freeze of the last glacial period ended. In North America, much of the runoff water from the melting ice sheets became trapped behind a ridge of debris deposited at the base of the shrinking glaciers. This formed immense meltwater lakes, the largest of which has been named Lake Agassiz. By 11,000 B.C., Lake Agassiz had expanded to cover almost half a million square kilometers of Canada and the northern United States-an area about the size of the Black Sea. Then, the inevitable happened. The natural dam (barrier) burst and the huge volume of glacial water poured out in an immense, surging flood. This sudden release of the trapped water caused an immediate jump in global sea levels.
Look at the four squaresthat indicate where the following sentence could be added to the passage
But the disappearing glaciers left behind some lasting features.
Insert Text Questions句子插入题
Where would the sentence best fit？Click on a square sentence to the passage.
10
The Younger Dryas event strongly affected Earth’s climate around 11.000 B.C.
Prose Summary Questions概要小结题
Select 3 answers
AThe gradual warming of 20,000 years ago at first caused desertification in some places, but by 11,000 B.C. conditions had begun to improve.
BNatufian hunter-gatherers followed populations of grazing mammals and eventually found a warm area east of the Mediterranean Sea to settle in.
CThe Natufians, who had been practicing agriculture during the last glacial period, found it difficult to continue doing so after 11,000 B.C.
DWhen the cold and dry conditions of the last glacial period ended, the water from melting ice sheets formed large lakes in North America.
EThe sudden release of water from the enormous Lake Agassiz stopped the transfer of heat from the equator to the north and led to a return of very cold conditions.
FSome Natufians, who had lived as sedentary hunter-gatherers during the warmer period, may have adapted to the Younger Dryas climate by planting seeds.
