懂你英语Level4unit2.docx

1、懂你英语Level4unit2懂你英语Level-4-unit-2Level 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 microsc

2、opic.Since that time, life has evolved 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 extinc

3、tion event, many life forms, or species 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

4、global conditions that life depends 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 sp

5、ecies on the planet, died out. When 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 ev

6、ents happened over a period of months 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 o

7、f so many plants and animals, the 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 event

8、s have helps to accelerate evolution.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, pe

9、rhaps we wouldnt be here today.-What 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

10、also believed that we have entered 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 cu

11、rrent mass extinction event? human 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, a

12、nd weather patterns are changing.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

13、longer any doubt that this is happening. 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 ex

14、tinction event is caused by humans.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 n

15、eeds for growth and repair.After 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 respira

16、tory system includes the nose and 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 imm

17、une system works.If an infection 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 bo

18、dy.The controlled use of fire allowed 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 hun

19、ting and more time for other things 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 transpor

20、tation.The development of tools and 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 understand

21、ing of electricity, telephones and 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 peo

22、ple needed to make things.With the 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

23、didnt go anywhere. I just spent an 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 do

24、ne in a long time? She hasnt spent 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.-Wh

25、at cant people live without? People 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

26、 got a divorce.-What was the wife 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 can

27、t wait.-What do they think is ironic 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

28、sleep, sleep someplace else. Employee: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: We

29、ll, if you dont like it, I suggest 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

30、 it is because we cant see inside 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

31、an apple but it cant be a banana.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 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