Unit3 Conservation一轮复习课文语法填空课件 2024届高考英语北师大版选择性必修第一册

Lesson 1 P52-55 新北师大选择性必修Book 1 Unit 3 CONSERVATION Extinctions, where entire species are _(彻底消除), 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 _ 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 _(vary). According to scientists, they include volcanic eruptions, asteroids _(hit) 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 _(blame). wiped out when various/varied hitting will be to blame Although it is not unusual for species to_(灭绝)naturally, the rate _which this is now happening is_(担忧的理由). 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, _(即), the“background extinction rate”. They found that human activity is causing species to die out 1,000 times faster _(比正常情况). There is a long list of reasons why so many species are dying out: air and water pollution, forests _(destroy), factory farming and overfishing. die out at cause for concern that is(to say) than normal being destroyed _(显然)human activity has negatively affected all other species on Earth, including animals and plants. If a sixth mass extinction occurs, scientists who have studied the issue believe that up to _(四分之三)of all species on Earth could die out. Of course, as we humans depend on so many species for our _(survive), we would also be at risk of dying out. Our world and our lives depend on the balance in nature between animals and plants. Without forests, we would have no air to breathe, and_(如果没有