the past?
1. What is the original earth’s atmosphere made up of? 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 for life to develop.
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.
Free Talk
1. How old is the universe? Several billion years ago.
2. How old is the earth? Between 4.5 and 3.8 billion years ago.
3. Which were the first creature or plants on earth?
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.
on the earth.
Para 5: The arrival of humans and their impact on the earth.
Answer the followingபைடு நூலகம்questions.
1. What is the original earth’s atmosphere made up of? 2. Why did scientists believe water is fundamental to the
Put the order of development of life.
• （10）1 Insects and amphibians appeared. • （7）2 Dinosaurs appeared. • （3）3 The earth became a solid ball. • （8）4 Small plants grew on the water. • （4）5 Reptiles appeared. • （9）6 Plants began to grow on dry land. • （6）7 The earth was a cloud of dust. • （1）8 Water appeared on the earth. • （5）9 Shellfish and other fish appeared. • （2）10 The universe began with a “Big Bang”. • （12）11 Clever animals with hands and feet appeared. • （11）12 Mammals appeared.
Read the passage carefully and analyse its structure.
Para 1:A widely accepted theory about the formation of the universe.
Para 2: The formation of the earth. Para 3: The importance of water for life. Para 4: The development of plants and animals
Fast reading
Read the passage quickly and find the main idea. A brief introduction on how the universe developed and how life began on the earth.
Careful reading
Unit 4
Astronomy: the science of the stars
How 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?
Very small air-breathing creatures. 4. Do you know what the order for the development of plants and animals is?
Ideas about how life began
reading
How Life Began on the Earth
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 SOLAR SYSTEM
地球 _E_a_r_t_h_ 木星 _J_u_p_i_te_r 火星 _M__a_r_s_ 水星 _M_e_r_c_u_r_y_
海王星 _N__ep__tu_n_e 土星 __S_a_t_u_r_n_ 天王星 _U__ra_n__u_s 金星 __V_e_n_u_s__ 冥王星 _P_l_u_t_o_