题目
题型:江苏高考真题难度:来源:
you think caused this change in colour? It is soil that has been washed into the river from the riverbank
or from the nearby fields.
Components of Soil
Soil is made up of a number of layers (层), each having its own distinctive colour and texture. The
upper layer is known as the litter. It acts like a blanket, limiting temperature changes and reducing water
loss. The topsoil layer is made up of small particles of rock mixed with rotten plant and animal matter
called humus (腐殖质), which is black and gives the topsoil its dark colour. This layer is usually rich in
nutrients, oxygen, and water. Below the topsoil is the subsoil, a layer that contains more stones mixed
with only small amounts of organic matter. This layer is lighter in colour because of the lack of humus.
Beneath the soil lies a layer of bedrock.
Soil forms from the bottom up. Over time bedrock is attacked by rain, wind, frost, and snow. It is
gradually broken down into smaller particles in a process called weathering. Plants begin to grow, and
rotten materials enrich the topsoil. Most of the soil in Eastern Canada, for example, was formed from
weathered rock that was exposed when the ice disappeared l2,000 years ago.
Water Beneath the Soil
Surface water collects and flows above the ground in lakes, ponds and rivers. Once in the soil or rock,
it is called groundwater. Gravity pulls groundwater through the soil in a process called percolation (渗透).
Eventually the water reaches a layer called the water table. Under this is bedrock through which water
cannot percolate.
As water percolates downward, it dissolves organic matter and minerals from the soil and carries them
to deeper layers. This causes a serious problem because plants require these nutrients for growth.
Soil pH
Soil can be acidic neutral or basic. The pH of the soil is determined by the nature of the rock from
which it was formed and by the nature of the plants that grow and rot in it.
The acidity of rain and snow can lower the pH of the groundwater that enters the soil. By burning fossil
fuels such as coal,oil and gasoline, humans have been contributing to higher levels of acidity in many soils.
When fossil fuels are burned, gases are released into the air and then fall back to earth as acid rain. Acid soil
increase the problem of carrying nutrients to lower soil levels. As nutrients are removed, soil is less fertile.
Plants grow more slowly in acidic soil, and also become easily attacked by diseases.
B. topsoil
C. humus
D. subsoil
B. The deeper layer of soil is darker in colour than the surface soil.
C. Air pollution is partially responsible for acid soil.
D. Groundwater tends to carry away nutrients for plant growth.
B. in the subsoil layer above bedrock
C. between the subsoil layer and bedrock
D. in the bedrock layer beneath the subsoil
are _____.
B. cleaned and purified by water
C. destroyed and carried away by water
D. mixed with water and become part of it
答案
核心考点
试题【阅读理解。 Have you ever noticed the colour of the water in a river or stream aft】;主要考察你对题材分类等知识点的理解。[详细]
举一反三
upon you. Air pressure is a wonderful force. When you swim underwater, you can feel water push down
your body. The air all around you does the same. However, your body is so used to it that you do not notice
this. The pressure is caused by a layer of air called the atmosphere. This layer surrounds the Earth, extending
to about five kilometers above the Earth"s surface.
The following experiment is an easy one that you can do at home. But make sure that you are supervised,
because you will need to use matches. Now for the experiment!
What you need
·A hard-boiled egg without the shell
·A bottle with a neck slightly smaller than the egg
·A piece of paper
·A match
Method
1) Check that the paper will sit firmly on the neck of the bottle.
2) Tear the paper into strips and put the strips into the bottle.
3) Light the paper by dropping a burning match into the bottle.
4) Quickly sit the egg on the neck of the bottle.
Result
Astonishingly, the egg will be sucked into the bottle. Your friends will be amazed when you show them
the experiment. But be careful when you handle matches.
Why it happened
As the paper burns, it needs oxygen and uses up the oxygen (air) in the bottle. The egg acts as a seal in
the neck of the bottle, so no more air can get inside. This reduces the air pressure inside the bottle. The air
pressure must equalize, so more air from outside must enter the bottle. The outside air pressure against the
egg and then the egg is pushed into the bottle! This proves that air is all around and that it is pressing down
on it.
B. You need to light the paper with a match.
C. The egg needs to be shelled.
D. The egg has to be perfectly placed on the neck of the bottle.
B. make a seal in the neck of the bottle
C. finish up the oxygen inside the bottle
D. produce more oxygen inside the bottle
B. It became salt without the shell.
C. The neck of the bottle was wide enough.
D. The outside air pressure forced it into the bottle.
B. the earth is surrounded by a layer of air called the atmosphere.
C. the pressure of air around us has a powerful force.
D. the air pressure is not equalized around us.
flights across the Atlantic Ocean, leaving hundreds of passengers stuck in airports.
Grirmsvom is one of the largest and most active volcanoes in Europe. What makes Grimsvom different
is that it lies under a huge glacier (冰川) of ice up to 12 maters thick. The hot volcano heats up the ice above
it, which then forms a layer (层) of water between the glacier and the volcano. This layer of water puts
pressure on the volcano, keeping it stable. As the water flows out from under the glacier, the pressure lifts.
The lava (岩浆) from the volcano then comes up to the surface. This is exactly what happened today.
Now, airlines have to make changes to their flights so as not to fly through the clouds of volcanic ash.
According to KLM. one of Europe"s biggest airlines, airplanes cannot go under the cloud or over it. Going
through the cloud can result in ash getting stuck in the airplane"s engines, causing damage to the plane.
The eruption has also caused problems for animals in Iceland. The volcano left ash and sharp. Glass-like
rocks all over the countryside. Farmers are keeping their animals inside to stop them from eating ash-covered
grass to the sharp object.
B. It lies under the sea
C. It is the largest volcano
D. It is lava affects the airlines
B. The low water temperature
C. The thick glacier
D. The water pressure
B. Airlines suffer from the loss of planes
C. It becomes dangerous for animals to eat outside
D. Farmers have lost many of their animals
B. a newspaper report
C. a class presentation
D. a geography textbook.
to hunt and rely on howling as an important means of communication among each other. There are different
explanations of a wolf"s howl and it appears that there may be more to discover.
One theory is that wolves howl to bond better together. It"s almost as if howling together helps the pack
stay together. Perhaps something is similar to people feeling a sense of involvement with each other when
singing a song together. But this theory may be wrong, explains Fred H. Harington, a professor who studies
wolf behavior.
Indeed, there have been times when wolves have been seen one moment howling in a chorus, and the
next, quarreling among each other. It appears that usually the lowest-ranking members of the pack may
actually be "punished" for joining in the chorus at times. So is howling a way to strengthen a social bond or
just a way to reconfirm status among its members? - Why do wolves howl for sure?
What is clear, however, is that howling is often used among packmates to locate each other. Hunting
grounds are distant and it happens that wolves may separate from one another at times. When this happens,
howling appears to be an excellent means of gathering.
Howling, interestingly, is a contagious behavior. When one wolf starts to howl, very likely others will
follow. This is often seen to occur in the morning, as if wolves were doing some sort of "roll call" where
wolves all howl together to report their presence.
B. the sense of accomplishment.
C. The act of hunting for something.
D. The sense of belonging to a group.
B. Wolves tend to protect their hunting grounds.
C. Wolves sometimes have quarrels after howling together.
D. Wolves of low rank are encouraged to join in the chorus.
B. find their companions
C. report the missing ones
D. express their loneliness
B. howling is a way of communication
C. howling often occurs in the morning
D. howling spreads from one to another
to read 2_____ short stories and then discuss which one was better. After reading both, I wasn"t sure. Over
the 3_____ several months, my professor taught me 4_____ one story was so much better than the other.
5_____ was rich in mclaphor (隐喻) and character development, while the other was humorous 6_____ too
shallow. I couldn"t see this at first. Yet, in a few months, my brain got reeducated and 7_____ could see the
difference between good and bad writing and could appreciate literature at a whole new level.
Going to college helps build a strong mind, which leads 8_____ greater success in one"s life.
African elephant is divided into two distinct (不同的) species.
The discovery was made by researchers at York and Harvard University when they were examing the
genetic relationship between the ancient woolly mammoth and mastodon modern elephants-the Asian
elepphant, African forest elephant, and African savanna elephant.
Once they obastain DNA sequences (序列) from two fossils (化石), mammoths and mastodons, the
team comparted them with DNA from modern elephants. They found their amazement that mordern forest
and savanna elephants are as distinct from each other as Asian elephants and mammoths.
The scientists used detailed genetic analysis to prove that the African savanna elephant and the African
forest elephant have been distinct species for several million years. The divergence of the two species took
place around the time of the divergence of Asian elephants and woolly mammoths. This result amazed all
the scientists.
There has long been debate in the scientific community that the two might be separate species, but this
is the most convincing scientific evidence so far that they are indeed different species.
Previously, many naturalists believed that African savanna elephants and African forest elephants were
two populationgs of the same species, despite the elephants" significant size differences. The savanna elephant
has an average shoulder height of 3.5 metres while the forest elephant has an averate shoulder double the
weight of the forest elephant. But the fact that they look so differrent does not neccssarily mean they are
different species. However, the proof lay in the analysis of the DNA.
Alfried Roca, assitant professor in the Department of Animal Sciences at t he University of Illinois, said,
"We now have to treat the forest and savanna elephants as two difficult units for conservation purpose.
Since 1950, all Afican elephants have been conserved as one species. Now that we know the forest and
savanna elephants have been distinct animals, the forest elephant should become a bigger priority (优先) for
conservation purposes."
B. the forest elephant
C. the savanna elephant
D. the maslodon elephant
B. exhibition
C. separation
D. examination
B. height
C. weight
D. population
B. The purpose of studying Afican elephant
C. The way to divide Afican elephants into two units
D. The renson for the distinction of African elephants
B. Amazing Experiments about Elephants
C. An Unexpected Finding ahout Elephants
D. A Long Scientifif Debate about Elephants
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