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Hello, I'm Margot Politis. Welcome to Study English, IELTS preparation.
Today we're going to see an animation about a process called salinity, that's where
land becomes damaged by too much salt.
We'll be looking at language you can use to describe processes, including transition
signals. Listen for how the process of salinity is described here.
One of the main causes of salinity is waterlogging. First, land is cleared for crops to grow.
Now, instead of trees pumping the water out of the ground, and keeping the salt stored,
whatever water the crops don't use percolates down into the soil.
Gradually, over a number of years, the earth gets wetter and wetter, and eventually it
waterlogs. Then, the water table starts to rise to the surface. As it rises, it dissolves
the tonnes of salt stored in the soil.
Once the water table comes to within two metres of the surface, it begins to evaporate. Lastly,
the sun extracts the moisture from the ground, leaving the salt concentrated on the surface.
The first casualties of this dramatic land change, and the dry land salinity that it
causes, are ecosystems.
We heard a description of a process. A process has a number of steps from beginning to end.
When describing a process, the first sentence, or topic sentence, should tell us what the
main idea of the paragraph is, and what the process is leading to.
Listen to the topic sentence.
One of the main causes of salinity is waterlogging.
One of the main causes of salinity is waterlogging.
This topic sentence tells us that the paragraph is about salinity, that is, land becoming
salty.
And the sentence tells us that one of the main causes of this problem is waterlogging.
So from this sentence, we expect that the paragraph will be about the process of land
becoming waterlogged, leading to salinity. When we describe a process, it is important
that the reader understands when each part of the process happens, what order things
happen in.
Listen again to the passage, and watch for the words that order the stages of the process.
First, land is cleared for crops to grow. Now, instead of trees pumping the water out
of the ground, and keeping the salt stored, whatever water the crops don't use percolates
down into the soil.
Gradually, over a number of years, the earth gets wetter and wetter, and eventually it
waterlogs. Then, the water table starts to rise to the surface. As it rises, it dissolves
the tonnes of salt stored in the soil.
Once the water table comes to within two metres of the surface, it begins to evaporate.
Lastly, the sun extracts the moisture from the ground, leaving the salt concentrated
on the surface.
She uses a range of transition signals to order the stages of the process.
One type of transition signal is ordinal numbers. Listen.
One of the main causes of salinity is waterlogging. First, land is cleared for crops to grow.
The ordinal numbers are first, second, third, fourth and so on.
These ordinal numbers can be used as adjectives to form phrases describing order.
We can either just start the sentence with:
First,
Second,
or we can use them in phrases like these:
The first step is
The second stage begins when
The third part is.
We can also add 'ly' to ordinal numbers to make adverbs:
firstly, secondly, thirdly, fourthly, etc.
Using these words is a very common and simple way of ordering stages in a process.
You can also use them to organise any group of ideas, examples or points in an argument.
Another type of transition signal is time phrases she uses is time phrases.
Gradually, over a number of years, the earth gets wetter and wetter,
Gradually, over a number of years, the earth gets wetter and wetter.
The phrase, "Gradually, over a number of years," tells us that this part of the process takes
place gradually, slowly, over a number of years, over many years.
It is a long, slow process.
Over a number of years is a time phrase. Using time phrases helps to make the descriptions
of processes clearer.
Other useful time phrases you might come across are:
at this stage
during this process
after several days
All of these phrases tell us when, or for how long, that stage in the process takes
place.
Listen again:
Then the water table starts to rise to the surface. As it rises, it dissolves the tonnes
of salt stored in the soil.
She says as it rises.
The word as tells us that two actions are taking place together, or simultaneously.
While the water table is rising to the surface, it dissolves the salt.
Other phrases indicating two actions taking place at the same time could be at the same
time, meanwhile.
There are some other adverbs you can use as transition signals. Which ones were used in
the passage?
Listen:
Now, instead of trees pumping the water out of the ground, and keeping the salt stored,
whatever water the crops don't use percolates down into the soil.
Gradually, over a number of years, the earth gets wetter and wetter, and eventually it
waterlogs. Then, the water table starts to rise to the surface. As it rises, it dissolves
the tonnes of salt stored in the soil.
She uses the adverbs now, eventually, then and lastly.
These all help to order events.
There are many other adverbs to choose from. Make sure you use a wide variety of them in
your writing and speaking, rather than just repeating the same ones.
Others include: finally, subsequently, later, afterwards.
OK. We're going to finish today by looking at some pronunciation.
There are a number of English words that can be used as both nouns and verbs.
However, in many cases, the pronunciation of these changes. This can be quite difficult
to get used to.
Listen to the word extracts in the passage:
Lastly, the sun extracts the moisture from the ground, leaving the salt concentrated
on the surface.
The sun extracts the moisture.
Extracts here comes from the verb to extract.
Where is the emphasis, or stress in this word?
It's on the second syllable exTRACT.
But extract is also a noun.
When it's a noun, it's pronounced EXtract. The emphasis is now on the first syllable.
And this pattern of first syllable emphasis for the noun form, and second syllable emphasis
for the verb form, is repeated with other words.
We have:
to exTRACT and an EXtract
to conTRACT and a CONtract
to consTRUCT and a CONStruct
and there are lots of others.
We have PROduce, that you eat and to proDUCE, to make
We have SUBject and Object but subJECT and obJECT
Let's test you. Try reading these sentences:
He objected to the subject of the lesson.
The farm produced fresh produce.
So you can see how the stress in words can change meaning. You'll have to practice
whenever you can!
And after all that, it must be time to go. See you next time on Study English.
Bye bye.
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盐浓度 (Study English - Series 1, Episode 18: Salinity)

122 分類 收藏
大呆危 發佈於 2018 年 6 月 25 日
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