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(共15张PPT)
Unit 3 Conservation
Lesson 1 The Sixth Extinction
(　　) 1. How many times up to today has life on Earth almost died out
a. Once. b. Five times. c. More than 10 times.
1.How much do you know about extinction Choose the option based on your knowledge.
(　　) 2. About what percent of all species on Earth became extinct during the mass extinction known as the “Great Dying”
a. Less than 10%. b. Nearly 50%. c. More than 90%.
(　　) 3. What do scientists think will cause the next mass extinction
a. Human activity. b. Natural causes. c. Unknown reasons.
b
c
a
2. Read and explore.
Read a text about extinction. Then check your answers in Activity 1.
①Extinctions, where entire species are wiped out, are not unusual in our Earth’s history. In fact, over 90 percent of all species that ever lived are now extinct. In the last 500 million years, there have been five times when life on Earth has almost ended. These include the third mass extinction, known as the “Great Dying”, which killed 90% to 96% of all species. And the fifth event, which occurred 66 million years ago, caused the death of the dinosaurs. The reasons for extinctions are varied. According to scientists, they include volcanic eruptions, asteroids hitting the Earth from space, changes in sea levels, the decrease of the oxygen content of the sea and global warming. Many scientists say we are now entering the Earth’s sixth mass extinction. This time, human activity will be to blame.
非限制性定语从句
限制性定语从句
限制性定语从句
非限制性定语从句
非限制性定语从句
承上启下
② Although it is not unusual for species to die out naturally, the rate at which this is now happening is cause for concern. A 2015 study by scientists who were based at Brown University and Duke University in the US, looked at how quickly species die out due to natural causes, that is, the “background extinction rate”. They found that human activity is causing species to die out 1,000 times faster than normal. There is a long list of reasons why so many species are dying out: air and water pollution, forests being destroyed, factory farming and overfishing. It is clear that human activity has negatively affected all other species on Earth, including animals and plants.
双重否定,表示肯定
It is adj for sb/sth to do sth
做...对某人/某物来说...
限制性定语从句
限制性定语从句
宾语从句
It is adj that ...
...是怎么样的
If a sixth mass extinction occurs, scientists who have studied the issue believe that up to three quarters of all species on Earth could die out. Of course, as we humans depend on so many species for our survival, we would also be at risk of dying out. Our world and our lives depend on the balance in nature between animals and plants. Without forests, we would have no air to breathe, and without clean water we would be unable to survive.
限制性定语从句
宾语从句
因为
the n between A and B
A和B之间的...
例：the competition between A and B
A和B之间的竞争
Can a sixth extinction be avoided Experts say that it is not yet too late, if we take action now. This would mean we have to significantly change the way we live. For example, we need to take steps to save endangered species, including setting up special areas where plants and animals can be protected. We need to change how we work and travel by using cleaner, more natural sources of energy, such as wind and solar energy. We also need to improve our farming methods to reduce water, air and land pollution. In short, if we want to survive, we need to stop destroying the planet that we live on and start to protect it.
be done(动词的过去分词) 被动语态
限制性定语从句
For instance
表目的
表条件
The Black Robin
Black robins are the birds that humans saved from extinction. In 1980, there were only five black robins left in the world. They all lived on a small island off the coast of New Zealand. Only one of those birds, a female called Old Blue, was able to lay eggs. Wildlife workers began a programme for raising black robin chicks. They protected Old Blue’s eggs, helped them to hatch, and took care of the chicks.（幼鸟） Thanks to their efforts, there are now more than 250 black robins, and the population（数量） is spreading. To help them survive, people are restoring their habitats and removing small animals that hunt them, such as mice and cats from the islands where they live.
Case Study
robin n. 知更鸟
habitat n. 栖息地
限制性定语从句
定语
多亏，由于
限制性定语从句
Meaning of extinction
How to avoid the sixth mass extinction
Main reasons that cause extinctions
Two notable（值得注意的） extinctions and their consequences
The number of extinctions that have occurred so far
Extinction
3.Read the plete the notes. Then talk about the different aspects of extinctions.
1. Meaning of extinction:
whole species wipe out
over 90% of all species that ever lived
the third mass extinction, which killed 90% to 96% of all species;
the fifth event, which occurred 66 million years ago, caused the death of the dinosaurs
volcanic eruptions, asteroids hitting the Earth from space, changes in sea levels, the decrease of oxygen content of the sea, global warming
3. Two notable extinctions and their consequences:
4. Main reasons that cause extinctions:
2. The number of extinctions that have occurred so far:
change the way we live, e.g. save endangered species, including setting up special areas where plants and animals can be protected; change how we work and travel by using cleaner, more natural sources of energy; improve our farming methods
5. How to avoid the sixth mass extinction:
1. What did scientists find out in 2015
The study found how quickly species die out due to natural causes, which is the “background extinction rate”. They found that human activity is causing species to die out 1,000 times faster than normal.
Because human activity has negatively affected all other species on Earth, including animals and plants.
2. Why does the writer think the sixth mass extinction will come
4.Read again. Answer the questions.
Because our world and our lives depend on the balance in nature between animals and plants.
3. Why does the writer believe we’ll probably die out if 75% of the Earth’s species die out
People protected Old Blue’s eggs, helped them to hatch, and took care of the chicks. People are restoring their habitats and removing pests like mice and cats from the islands where they live. It’s never too late to protect species.
4. What did people do in the case study to protect black robins Which claim(s) did the case study support in the text
In the last 500 million years, there have been five mass extinction events on Earth. In the third event, which 1. __________ the “Great Dying”, 90% to 96% of all species 2. _________. Of course, species died out due to many causes. But nowadays, human activity 3. ___________ all types of species that we 4. ___________ for living. We need to 5. ___________ to avoid the sixth mass extinction. We should 6. __________ to save endangered animals and plants, and 7. _______ special areas to 8. ___________ them before the next extinction comes that may 9. _________ the entire species.
7.Complete the paragraph about extinctions using the correct form of the phrases below.
is known as
died out
has affected
depend on
take action
take steps
set up
take care of
wipe out
die out be known as have affected depend on wipe out
take steps take action set up take care of
8.Read the sentences and discuss which word(s) the clauses (in italics) refer to.
1. Extinctions, where entire species are wiped out, are not unusual in our Earth’s
history.
“Extinctions”
2. These include the third mass extinction, known as the “Great Dying”, which
killed 90% to 96% of all species.
“Great Dying”
3. A 2015 study by scientists who were based at Brown University and Duke
University in the US, looked at how quickly species die out due to natural
causes...
“scientists”
4. If a sixth mass extinction occurs, scientists who have studied the issue believe that up to three quarters of all species on Earth could die out.
“scientists”
5. We need to take steps to save endangered species, including setting up special areas where plants and animals can be protected.
“special areas”
Which of the clauses above:
(1) give information to identify the persons / objects. (_____________)
(2) give extra information about a person or a thing, which can be left out.
(________________)
3,4,5
1,2
Thank You

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