Astronomy教案

2.it was begun by chance (or accident); or
3.the answer is not sure.
shown this way, the question is:
 
additional materials
complete the summary of the story with one word in each blank.
how life began on the earth
after the “big bang” came a   1   of energetic dust, the earth. dust combined into a ball, moving   2   the sun. the earth became violent. then it   3  loudly. in time, the water vapor was produced, making the earth’s atmosphere   4   down. water then appeared on the  5   . the earth was to be different from other planets going round the  6   . water disappeared from other planets. but it stayed on  7  .
small plants began developing   8   the water.
years later green plants came into  9  . the air then was   10   with oxygen.
millions of years later, small  11   animals were found to be living on the  12   , in the sea. they spread all over the earth, moving   13    the earth, putting too much carbon dioxide into the atmosphere which   14   heat from escaping from earth into space.
in the end the earth may become too hot to live   15   .
（keys: 1. cloud 2. around 3. exploded 4. cool 5. surface 6. sun 7. earth 8. in 9. being 10. filled 11. clever 12. land 13. around 14. prevents 15. upon）
comprehension questions
1. what forms the earth’s atmosphere?
a. carbon dioxide, oxygen. b. carbon dioxide, oxygen, poisonous gas.
c. water vapour, carbon dioxide, oxygen, nitrogen.
d. water vapour, carbon dioxide, oxygen, nitrogen and other gases.
2. can you tell what is the “special qualities” of the earth according to the passage?
a. the earth goes around the sun. b. the earth was solid shape which was last.
c. there are animals and human beings live on it. d. water remains on the surface of the earth.
3. what kind of factor improve the progress of life?
a. water forms on the earth’s surface. b. green plants began to appear on land.
c. the air is full of carbon dioxide. d. animals began to appear such as insects, amphibians, est.
4. what is the main idea of this passage?
a. it tells us how does life begin to appear on the earth.
b. it tells us why does green plants grow before animals.
c. it tells us water plays an important role in the development of life.
d. d. it tells us carbon dioxide is the reason why living beings will die in the future,