懂你英语L4U2-11页文档资料.doc
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1、如有侵权,请联系网站删除,仅供学习与交流懂你英语L4U2【精品文档】第 11 页懂你英语L4-Unit2 1 Extinction EventsLevel4 Unit2 1 ListeningExtinction EventsThe Earth was formed about 4.6 billion years ago.The first life appeared about a billion years later.The first plants didnt appear until around 2 billion years ago. Until about 580 millio
2、n years ago, life forms were small and microscopic. Since that time, life has evolved into many different types, or species. However, scientists estimate that more than 99% of them are now extinct.There have been several extinction events in the history of the Earth. In an extinction event many life
3、 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 these can change the global conditions
4、 that life depends on.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. When the asteroid hit the earth, it started a chain of event
5、s. A chain of events is a series of events linked together, like a chain.This particular chain of events 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
6、many months. Without enough sunlight, plants and plant-eating animals quickly died. With the deaths of so many plants and animals, the food chain collapsed. This led to the deaths of many more species.Mass extinction events have played an important part in the evolution of life. In fact, some extinc
7、tion events have helped 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 a higher state. Without extinc
8、tion events, perhaps we wouldnt be here today.Scientists estimate that there have been at least 5 mass extinctions in the last 540 million years. They also believe that we have entered a new extinction event. Species are becoming extinct at a much faster rate than before. Instead of asteroids or vol
9、canic eruptions, the current event is the result of human activities. Human activities, for example, have led to global warming.Global warming is the result of an increase in carbon gases in our atmosphere. These gases trap heat from the sun, so the Earth is getting warmer. As a result, sea levels a
10、re rising and 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.There is no longer any doubt that this is happening. Species of life are disappearing at a
11、n 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 humans.)Level4 Unit2 1 VocabularyBody SystemsTh
12、e 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 blood vessels that carry oxygen-rich bloodfrom the heart are called arteries.)The digestive system breaks down and absorbs food into the body.
13、 Its supplies the energy that the body needs for growth and repair. After digestion, excess food is turned into waste and eliminated from the body. (The digestive system is where food is broken down and absorbed into the body.)The nervous system includes the brain,spinal cord and nerves. This is you
14、r bodys control system. It controls your muscles and organs, including your circulatory and digestive system. (The nervous system regulates your heartbeat and digestion.)The respiratory system includes the nose and lungs. It brings air and oxygen into the body and removes carbon dioxide. The lungs a
15、re 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 invades the body, the immune system attacks it.Great DiscoveriesThe controlled us
16、e of fire allowed people to cook food and survive in the colder climates. Fire provided light so that people could work andsocialize for longer hours.With the invention of agriculture, people could grow food andsettle into communities. By growing food, people could spend less time hunting, and more
17、time for other things such as art. (With the development of agriculture, people had more time for other activities.)The domestication of animals allowed people to raise and use animals for food and work. By raising herds of animals such as sheep, humans had a regular supply of meat and clothing. The
18、 strength of animals such as horses andoxen was used for work and transportation.The development of tools and machines has resulted in more efficientmanufacturing and construction. With better tools and machines, work can be done with fewer people and at much lower costs. (The use of machines has re
19、duced the number of people needed to make things.)The development of science and engineering has improved many things, including communications. With an understanding of electricity, telephones and radios allow people to communicate over long distances. (Science and engineering have changed the way
20、we communicate with each other.)Level4 Unit2 Part1 DialogueSmartphone AddictionI took a vacation last night.What are you talking about?Where did you take your vacation?I didnt go anywhere.I just spend an evening without my smartphone.How was it?It was great. I got a real magazine and read it with no
21、 interruption.It was very peaceful.Yes, I havent done that in a long time.You know what?Im beginning to hate smartphones.Really? but you cant live without one, right?Yes, thats the problem.These things are changing the way people live.Yes, I just saw a documentary about that.A husband was complainin
22、g to his wife that she was spending too much time on her smartphone.what happened? Did they get a divorce?You guessed it. In the end, they got a divorce.Its a bit ironic, dont you think?Smartphone were supposed to bring people together, but they are pulling people apart.Yes, you are right.Hey, just
23、a minute. Ive got a message on my smartphone, and it cant wait.Rude BossHey, wake up and get back to work.Whats wrong with you?Im on my break sir, and I have a bad headache.Well, we are not paying you to sleep.If youre going to sleep, sleep someplace else.Yes, sir, sorry, it wont happen again.It had
24、 better not.Just a minute.Dont talk to me like that.What did you say?You hurt me. you dont have to treat people like that.Well, if you dont like it, I suggest you leave.OK, I will. Ive had enough of you.Ill get a job somewhere else.(The manager treats the employees in a threatening manner.)(The empl
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