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课件网) Unit 3 Conservation Lesson 1 The Sixth Extinction 重点单词 1．_____ n. 物种，种 2．_____ adj. 异常的；不平常的 3．_____ adj. 大量的 4．_____ adj. 各种各样的，形形色色的 5．_____ vi. & vt. 减少 n.减少；减少的量 6．_____ vt. 责怪，指责 7．_____ vt. 影响 8．_____ adj. 濒危的 9．_____ adj. 太阳光（能）的 10．_____ vi. & vt. （使）孵化 11．_____ vt. （使）恢复 species unusual mass varied decrease blame affect endangered solar hatch restore 重点词块 1．at the rate of… _____ 2．be based on… _____ 3．lay eggs _____ 4．be at risk _____ 5．wipe out _____ 6．die out _____ 7．up to… _____ 8．in short _____ 9．according to _____ 10．take steps _____ 11．be to blame _____ 以……的速度/比例 基于…… 产卵/下蛋 处境危险；受到威胁 彻底毁灭 消失；绝迹；灭绝 高达…… 简而言之 根据；按照 采取措施 把……归咎于 ( ) 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 hum ... ...
