文档介绍：Unit 4
Astronomy: the science of the stars
How much do you know about the universe?
What are the names of the eight oceans and seas to ensure a following chain reaction, which made it possible for life to develop.
What is the original earth’s 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 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 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.
（ 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.
8
7
5）
6
4
1
10
3
9
2
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 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 fish
Some animals (amphibian & insects) came to land.
Reptile appeared.
dinosaurs
mammals
Man had evolved from apes.
We are making the world better.
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!