1、Level 4 unit 2 part1ListeningThe earth was formed by about 4.6 billion years ago. The first life appeared about a billion years later. The first plaints didnt appear until around 2 billion years ago.Until about 580 million years ago, life forms were small and microscopic.Since that time, life has ev
2、olved into many different types or species.However, scientists estimate that more than 99% of them are now extinct. -When did the first plant appear on earth? about 2 billion years ago.There have been several extinction events in the history of the Earth.In an extinction event, many life forms, or s
3、pecies of life, die out.The causes of mass extinction events are unsolved mysteries.These events are not predictable, and can happen at any time.Scientists think that some of them were started by asteroid impacts or volcanic eruptions.Events like this can change the global conditions that life depen
4、ds on.-What happens in an extinction event? Many species of life become extinct. One major extinction event happened about 66 million years ago.That event may have been started by a large asteroid that hit the Earth.As a result, the dinosaurs and about half of all species on the planet, died out. Wh
5、en the asteroid hit the Earth, it started a chain of events.A chain of events is a series of events linked together, like a chain.-What may have caused the extinction of the dinosaurs?An asteroid hit the earth and started a chain of events.This particular chain of events happened over a period of mo
6、nths and years. When the asteroid hit the Earth, it caused a huge cloud of dust to enter the atmosphere. This cloud of dust blocked the sun and darkened the Earth for many months. Without enough sunlight, plants and plant-eating animals quickly died.With the deaths of so many plants and animals, the
7、 food chain collapsedThis led to the deaths of many more species. -What caused the food chain to collapse? The deaths of many plants and plant-eating animals.Mass extinction events have played an important part in the evolution of life. In fact, some extinction events have helps to accelerate evolut
8、ion.For example, some mammals lived through the age of the dinosaurs, but they couldnt compete. When the dinosaurs were removed, the mammals were able to compete more successfully. Once they could compete, mammals evolved to higher state.Without extinction events, perhaps we wouldnt be here today.-W
9、hat may accelerate the evolution of mammals? the extinction of dinosaurs.Mammals couldnt compete successfully with the dinosaurs, so their evolution was blocked. Scientists estimated that there had been at least 5 mass extinctions in the last 540 million years. They also believed that we have entere
10、d a new extinction event.Species are becoming extinct at a much faster rate than before.Instead of the asteroid or volcanic eruptions, the current event is a result of human activities.Human activities, for example, have led to global warming. -What is causing the current mass extinction event? huma
11、n activities-What do scientists believe has already started? a new extinction event.Global warming is a result of an increasing in carbon gases in out atmosphere. These gases trap heat from the sun, so the Earth is getting warmer.As a result, sea levels are rising, and weather patterns are changing.
12、In addition, we humans are destroying the habitats of many plants and animals. Cutting down forests, and polluting rivers destroys the habitats of many forms of life. -Why are sea levels rising? With the rise in temperature, the polar icecaps are melting.There is no longer any doubt that this is hap
13、pening. Species of life are disappearing at an increasing rate.Global temperatures are rising and weather patterns are changing.Scientists are warning us that fast action is necessary to save our future. If we dont act, we may go the way of the dinosaurs. This new extinction event is caused by human
14、s.VocabularyThe bodys circulatory system includes the heart and blood vessels.The heart pumps blood to all parts of the body through a network of arteries and veins.The digestive system breaks down and absorbs food into the body.It supplies the energy that the body needs for growth and repair.After
15、digestion, excess food is turned into waste and eliminated from the body.The nervous system includes the brain, spinal cord, and nerves.This is your bodys control system.It controls your muscles and organs, including your circulatory and digestive systems.The respiratory system includes the nose and
16、 lungs.It brings air and oxygen into the body and removes carbon dioxide.The lungs are where oxygen enters the bloodstream and carbon dioxide is removed.The immune system protects the body against infections and diseases.Sneezing and fever are examples of how the immune system works.If an infection
17、invades the body, the immune system attacks it.The nervous system regulates your heartbeat and digestion.For some diseases, the immune system uses white blood cells and antibodies to attack it.The digestive system is where food is broken down and absorbed into the body.The controlled use of fire all
18、owed people to cook food and survive in colder climates.Fire provided light so that people could work and socialize for longer hours.With the invention of agriculture people could grow food and settle into communities.By growing food, people could spend less time hunting and more time for other thin
19、gs such as art.The domestication of animals allowed people to raise and use animals for food and work.By raising herds of animal such as sheep, humans had a regular supply of meat and clothing.The strength of animals such as horse and ox was used for working transportation.The development of tools a
20、nd machines has resulted into more efficient manufacture and construction.With better tools and machines work can be done with fewer people at much lower cost.The development of science and engineering has improved many things including communications.With understanding of electricity, telephones an
21、d radios allow people to communicate over long distances.Science and engineering breakthroughs are rapidly changing the way we live our lives.Science and engineering have changed the way we communicate with each other.The use of machines has reduced the number of people needed to make things.With th
22、e development of agriculture, people had more time for other activities.The ability to raise herds of animals gave human a regular supply of meat and clothingDialogueM: I took a vocation last night.W: What are you talking about? Where did you take your vocation?M: I didnt go anywhere. I just spent a
23、n evening without my smartphone.W: How was it?M: It was great. I got a real magazine and read it with no interruption. It was very peaceful. W:Yes, I havent done that in a long time.-If someone is interrupted, they have to -stop what they are doing.-What hasnt she done in a long time? She hasnt spen
24、t time without her smartphone.-What made the evening different? He didnt use his smartphone.M: You know what? Im beginning to hate smartphones.W: Really? But you cant live without one, right?M: Yes, thats the problem. These things are changing the way people live.-What cant people live without? Peop
25、le cant live without smartphones.-How does he feel about smartphones? Hes beginning to hate them.W: Yes, I just saw a documentary about that. A husband was complaining to his wife that she was spending toomuch time on her smartphone.-What happened to the couple? They got a divorce.-What was the wife
26、 spending too much time doing? playing on her smartphone.M: Its a bit ironic. Dont you think? Smartphones were supposed to bring people together, but they are pullingpeople apart.W: Yes, youre right.M: Hey, just a minute. Ive got a message on my smartphone and it cant wait.-What do they think is iro
27、nic about smartphones? Instead of bringing people together, they are pulling them apart.Boss: Hey, wake up and get back to work. Whats wrong with you?Employee: Im on my break, sir. And I have a bad headache.Boss: Well, were not paying you to sleep. If youre going to sleep, sleep someplace else. Empl
28、oyee:Yes, sir. Sorry. It wont happen again.Boss: You had better not.-How did the employee treat the manager? respectfully.Employee: Just a minute. Dont talk to me like that.Boss: What did you say?Employee: You hurt me. You dont have to treat people like that.Boss: Well, if you dont like it, I sugges
29、t you leave.Employee: OK, I will. Ive had enough of you. Ill get a job somewhere else.-How does the employee feel? angry.Level 4 unit 2 part2ListeningThis man is holding a piece of fruit in his hand.The piece of fruit is either an orange or an apple.We cant see which it is because we cant see inside
30、 the box.The probability that it is an orange is equal to the probability that it is an apple.It may be an apple and it may be an orange.Its got to be one or the other.It cant be anything else.-Whats the probability that its a banana? The probability is 0%.It may be an apple but it cant be a banana.
31、Now lets look at it from the mans point of view.From his point of view, the probabilities are different.From his point of view, the probability that he has an orange is 100% or 0%. Thats because he knows what he has.For him, there is no uncertainly.If he has an orange, the probability is 100%.If he
32、doesnt have an orange, the probability is 0%.He either has it, or he doesnt.-From our point of view, whats the probability that its an orange? -50%.From our point of view, the probability that he has an orange is 50%.From his point of view, the probability that he has an orange is 100% or 0%. Sothe
33、probability depends on your point of view.-Whats the probability that its a banana? a 0% probability.The probability depends on your point of view, or how much you know.People see things from different points of view. This often leads to arguments between people.Here are some examples.From this mans
34、 point of view, he is relaxing.He needs to relax because he has been working too hard. He hasnt been getting enough sleep.-If his wife shouts at him and tells him to get up and do something -he may shout back and refuse to help her.His wife sees things differently.She isnt aware of how hard he has b
35、een working.From her point of view, he is doing nothing.However, she knows what needs to be done around the house. Itisnt fair that she had to work while he does nothing.-If he gets up and helps her -She may not appreciate his help.-From the husbands point of view, whats he doing? He is relaxing.Whe
36、n people see things from different points of view, they often come to different conclusions. These differences can cause real communication problems.People often argue with each other because they see things from a different point of view.VocabularyEarthquakes are caused by forces deep within the ea
37、rth.When the earth shakes, buildings can collapse, and people can be buried inside.An explosion is a rapid, violent, release of energy.Explosions can be caused by chemical reactions, such as inside an engine.A spark can ignite mixture of gases, and release energy for good or destructive purposes.Acc
38、idents are often caused by people doing foolish things, or by not being careful.One major cause of accidents is driving too fast.Accidents with fire can be very serious and can result in very painful injuries.Epidemics are the rapid spread of diseased such as the flue or Ebola.Throughout history, ep
39、idemics have killed millions of people.Storms are caused by changes in the atmosphere, results in high winds and heavy rains.Thunderstorms are caused by electric charges in the atmosphere that produce lighting, which can cause forest fires.Some storms cause flooding, and major damage to homes and ci
40、ties.To reduce the danger of an explosion, its important to prevent gas leaks inside the home.Many forest fires are caused by lightning.Epidemics have killed more people than all wars and natural disasters.Followers of the Islam religion are called Moslems (Muslims).These Moslems are praying inside
41、mosque.Moslems are called to prayer five times a day, beginning just before sunrise.Christianity is based on the teachings of Jesus Christ, Who lived more than 2000 years ago.Christians believe that Jesus is the son of God.Christians often gather in churches or cathedrals to worship.Follower of the
42、Judaism are somewhere called Jews.These Jews are meeting inside synagogue, which is a place of worship and study.Judaism was founded over 3500 years ago, in the Middle East.Judaism was based on the teachings of Moses, who they believed is the most important prophet. Buddhismbegan in India, and is based on the teachings of the Buddha.The religion is about 2500 years old.Some Buddhists practice a form of the meditation in which they empty their mind of any thought.Hinduism is the worlds third most popular religion and is the main
