懂你英语L4-Unit2 1 Extinction Events
Level4 Unit2 1 Listening Extinction Events
The Earth was formed about 4.6 billion years ago.The first life appeared about a billion years later.The first plants didn't appear until around 2 billion years ago. Until about 580 million 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 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 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 events. 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 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 extinction events have helped to accelerate evolution. For example, some mammals lived through the age of the dinosaurs, but they couldn't 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 extinction events, perhaps we wouldn't 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 volcanic 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 are 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 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 don't act, we may go the way of the dinosaurs. (This new extinction event is caused by humans.) Level4 Unit2 1 Vocabulary Body Systems
The body's 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. It's 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 your body's 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 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 invades the body, the immune system attacks it. Great Discoveries
The controlled use 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 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 strength of animals such as horses andoxen was used for work and transportation.
The development of tools and machines has resulted in more efficient manufacturing and construction. With better tools and machines, work can be done with fewer people and at much lower costs. (The use of machines has reduced 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 we communicate with each other.)
Level4 Unit2 Part1 Dialogue Smartphone Addiction I took a vacation last night. What are you talking about? Where did you take your vacation? I didn't 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 interruption. It was very peaceful.
Yes, I haven't done that in a long time. You know what?
I'm beginning to hate smartphones. Really? but you can't live without one, right? Yes, that's the problem.
These things are changing the way people live. Yes, I just saw a documentary about that.
A husband was complaining 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. It's a bit ironic, don't you think?
Smartphone were supposed to bring people together, but they are pulling people apart. Yes, you are right.
Hey, just a minute. I've got a message on my smartphone, and it can't wait.