Life in the Universe
Many scientists today are convinced that life exists elsewhere in the universe---life probably much like that on our own planet. They reason in the following way.
As far as astronomers can determine, the entire universe is built of the same matter. They have no reason to doubt that matter obeys the same laws in every part of the universe. Therefore, it is reasonable to guess that other stars, with their own planets, were born in the same way as our own solar system. What we know of life on earth suggests that life will arise wherever the proper conditions exist.
Life requires the right amount and kind of atmosphere. This eliminates all those planets in the universe that are not about the same size and weight as the earth. A smaller planet would lose its atmosphere; a larger one would hold too much of it.
Life also requires a steady supply of heat and light. This eliminates double stars, or stars that flare up suddenly. Only single stars that are steady sources of heat and light like our sun would qualify.
Finally, life could evolve only if the planet is just the right distance from its sun. With a weaker sun than our own, the planet would have to be closer to it. With a stronger sun, it would have to be farther away.
If we suppose that every star in the universe has a family of planets, then how many planets might support life? First, eliminate those stars that are not like our sun. Next eliminate most of their planets; they are either too far from or too close to their suns. Then eliminate all those planets which are not the same size and weight as the earth. Finally, remember that the proper conditions do not necessarily mean that life actually does exist on a planet. It may not have begun yet, or it may have already died out.
This process of elimination seems to leave very few planets on which earthlike life might be found. However, even if life could exist on only one planet in a million, there are so many billions of planets that this would still leave a vast number on which life could exist.
1. Astronomers believe that matter in different parts of the universe
A) has different laws.
B) has one common law.
C) shares the same laws
D) shares no common law.
2. The existence of life depends on all of the following factors EXCEPT
A) the right amount of atmosphere.B) our own solar system.
C) steady heat and light D) the right distance from the sun.
3. Which of the following statements is INCORRECT?
A) The planet must be as big and heavy as the earth.
B) Proper conditions are essential to the existence of life
C) Double stars can provide steady light and heat.
D) The distance between a planet and its sun should be right.
4. What kind of planet might NOT support life?
A) Most of the planets of the stars.
B) Stars similar to our sun.
C) Planets similar to the earth.
D) Planets with proper conditions.
5. At the end of the passage the author suggests that
A) it is impossible for life to exist on planets.
B) earthlike life could only exist on a few planets.
C) life could exist on only one planet in a million.
D) life could exist on a great number of planets.
KEY:CBCAD
英文睡前故事 第80集:The Bog Baby
英文睡前故事 第100集:What Friends Do Best
英文睡前故事 第101集:What Pet to Get
英文睡前故事 第93集:Thump Quack Moo
英文睡前故事 第77集:The Best Gift of All
英文睡前故事 第82集: The Dragon Festival
英文睡前故事 第56集:Once There Was a House
英文睡前故事 第83集:The Fox in the Dark
英文睡前故事 第70集:Stuck in the Mud
英文睡前故事 第69集:Small Mouse Big City
英文睡前故事 第49集:Miki
英文睡前故事 第67集:Six Dinner Sid
英文睡前故事 第99集:What Does Daddy Do
英文睡前故事 第79集:The Blackest Hole in Space
英文睡前故事 第48集:Magic Sky
英文睡前故事 第47集:Look Out Stripey Horse
英文睡前故事 第81集:The Cow That Laid an Egg
英文睡前故事 第68集:Small Knight and George
英文睡前故事 第73集:Tappity Tap What Was That
英文睡前故事 第59集:Pete the Sheep
英文睡前故事 第72集:Tabby McTat
英文睡前故事 第89集:The Pencil
英文睡前故事 第64集:Russell the Sheep
英文睡前故事 第87集:The Magic Shoebox Farm
英文睡前故事 第63集:Ruby Sings the Blues
英文睡前故事 第71集:Super Daisy and the Peril of Planet Red Fox
英文睡前故事 第62集:Princess Smartypants Breaks the Rules
英文睡前故事 第91集:The Star Faced Crocodile
英文睡前故事 第84集:The Hipponotamus
英文睡前故事 第76集:That Rabbit Belongs to Emily Brown
| 不限 |
| 英语教案 |
| 英语课件 |
| 英语试题 |
| 不限 |
| 不限 |
| 上册 |
| 下册 |
| 不限 |