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1、Unit 4 Astronomy: the science of the starsHow much do you know about the universe?What are the names of the eight planets that circle our sun? What is their order from the sun?地球地球 _木星木星 _火星火星 _水星水星 _海王星海王星 _土星土星 _天王星天王星 _金星金星 _EarthJupiterMarsMercuryNeptuneSaturnUranusVenusTHE SOLAR SYSTEM 1. How o
2、ld is the universe?2. How old is the earth?3. Which were the first creature or plants on earth?4. Do you know what the order for the development of plants and animals is?Several billion years ago.Between 4.5 and 3.8 billion years ago.Very small air-breathing creatures.Free TalkIdeas about how life b
3、egan readingHow Life Began on the EarthFast readingRead the passage quickly and find the main idea.A brief introduction on how the universe developed and how life began on the earth. Careful readingPara 1: Para 2:Para 3:Para 4: Para 5: A widely accepted theory about the formation of the universe.The
4、 formation of the earth.The importance of water for life.The development of plants and animals on the earth.The arrival of humans and their impact on the earth.Read the passage carefully and analyse its structure.earth, atmosphere and waterlife developmenthuman beings1. What is the original earths a
5、tmosphere made up of? 2. Why did scientists believe water is fundamental to the development of life?3. How did water come into being on the earth?4. Which kind of life-being first appeared on the earth, plants or animals? Why?5. Why were mammals different from all life forms in the past?Answer the f
6、ollowing questions.Carbon, nitrogen, water vapour, and other gases.2. Why did scientist believe water is fundamental to the development of life?Because water allowed the earth to dissolve harmful gases and acids into the oceans and seas to ensure a following chain reaction, which made it possible fo
7、r life to develop. 1.What is the original earths atmosphere made up of?3. How did water come into being on the earth?The explosion of the earth produced water vapor, which turned into water when the earth cooled down.4. Which kind of life-being first appeared on the earth, plants or animals? Why?At
8、first, small plants began to appear on the surface of the water, they produce oxygen, which encouraged the later development of early shellfish and all sorts of fish.5. Why were mammals different from all life forms in the past?They were different because they produced their young from within their
9、bodies and produce milk to feed them.（ ）1 Insects and amphibians appeared.（ ）2 Dinosaurs appeared.（ ）3 The earth became a solid ball.（ ）4 Small plants grew on the water. （ ）5 Reptiles appeared.（ ）6 Plants began to grow on dry land.（ ）7 The earth was a cloud of dust.（ ）8 Water appeared on the earth.（
10、 9 Shellfish and other fish appeared.（ ）10 The universe began with a “Big Bang”.（ ）11 Clever animals with hands and feet appeared.（ ）12 Mammals appeared.875）64110392 Put the order of development of life. 12 11 Let review the evolution of life on the earth.After the “Big Bang”, the earth was full of
11、water.Original cells appeared in the ocean.The cells in the water began to separate. Small plants came into being.Early shellfish and all sorts of fishSome animals (amphibian & insects) came to land.Reptile appeared. dinosaurs dinosaurs mammalsMan had evolved from apes. We are making the world bette
12、r.We are making the world worse.Discussion Because they are putting too much carbon dioxide into the atmosphere.The earth may become too hot to live on .The earth is becoming hotter and hotter! solar energy plant trees recycle rubbish prevent desertificationsave water purify airWhat can we do to tak
13、e care of the earth?Whether life will continue on the earth depends on human beings.精讲点拨精讲点拨The earth became so violent that it was not clear whether the shape would last or not. What many scientists believe is that the continued presence of water allowed the earth to dissolve harmful gases and acids into the oceans . 分析句子分析句子：Homework1. A composition about What we can do to take care of the earth?2. Read and retell the passage to learn the important and difficult language points.
