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.
答案: CBCAD
雅思写作常用词汇:改良/改进
雅思写作忌用的两种表达方法
雅思写作范文:记忆的方法
雅思话题作文思路点睛:频繁换工作
雅思写作常用词汇:处在争论中
雅思写作范文赏析与评改:跨国公司
雅思写作范文:幸福感的来源
雅思写作思路分析:传统游戏与现代游戏
雅思话题作文思路点睛:工作满意度
雅思写作切题的观点很重要 词汇次之
雅思写作中不能用到的减分表达
雅思话题作文思路点睛:雇佣员工的标准
轻松一刻 说说雅思写作中的那些Chinglish
雅思写作常用词汇:就像/正如
雅思写作常用词汇:介入/干预/调停
雅思写作议论性精彩句型10例
雅思写作常用词汇:首选/优先的
雅思写作常用词汇:生态平衡
雅思写作技巧分享:小作文常用的写作技巧
雅思写作常用词汇:守法
雅思写作范文:美国成年人整体婚姻状况
雅思写作常用词汇:囚禁/关押/捕获
雅思写作常用词汇:野蛮的
雅思写作常用词汇:反对/不赞成
雅思写作常用词汇:野生动物保护
雅思写作范文:游戏的利弊
烤鸭分享:个人整理的雅思小作文写作资料
雅思写作常用词汇:疫苗
雅思写作常用词汇:侵犯
雅思写作范文:政府是否应该限制广告内容
不限 |
英语教案 |
英语课件 |
英语试题 |
不限 |
不限 |
上册 |
下册 |
不限 |