If the population of the earth goes on increasing at its present rate, there will eventually not be enough resources left to sustain life on the planet.By the middle of the 21st century,if present trends continue, we will have used up all the oil that drives our cars,for example.Even if scientists develop new ways of feeding the human race,the crowded conditions on earth will make it necessary for lus to look for open space somewhere else. But none of the other planets in our solar system are capable of supporting life at present. One possible solution to the problem, however,has recently been suggested by American scientist, Professor Carl Sagan.
Sagan believes that before the earths resources are compleetely exhausted it will be possible to change the atmophere of Venus and so create a new world almost as large as earth itself. The difficult is that Venus is much hotter than the earth and there is only a tiny amount of water there.
Sagan proposes that algae organisms that can live in extremely hot or cold atmospheres and at the same time produce oxygen,should be bred in condition similar to those on Venus.As soon as this has been done, the algae will be placed in small rockets. Spaceship will then fly to Venus and fire the rockets into the atmosphere .In a fairly short time, the alge will break down the carbon dioxide into oxygen and carbon.
When the algae have done theri work, the atmosphere will become cooler,but befor man can set foot on Venus it will be neccessary for the oxygen to produce rain. The surface of the planet will still be too hot for man to land on it but the rain will eventually fall and in a few years something like earth will be reproduced on Venus.
1.Inte long run, the most insoluble problem caused by population growth on earth will probably be the lack of ______.
a.food
b.oil
c.space
d.resources
2.Carl Sagan believes that Venus might be colonized from earth because _____
a.it might be possible to change its atmosphere
b.its atmosphere is the same as the earths
c.there is a good supply of water on Venus
d.the days on Venus are long enough
3.On Venus there is a lot of ________.
a.water
b.carbon dioxide
c.carbon monoxide
d.oxygen
4.Algae are plants that can____.
a.live in very hot temperatures
b.live in very cold temperatures
c.manufacture oxygen
d.all of the above
5. Man can land on Venus only when_______.
a.the algae have done their work
b.the atmosphere becomes cooler
c.thereis oxygen
d.it rains there
答案:cabdd
儿童英语歌曲 小懒虫玛丽
小学四年级英语课堂教学论文
小学英语教学论文 英语和音乐相结合
小学英语教学中实施自主教育初探 论文
儿童英语歌谣 Bought Me a Cat
小学英语课堂教学论文:歌谣的创设
小学英语教学论文:想象中创新
小学英语歌谣 One,One,One
论文 英语教学中的文化意识
对民办学校小学英语教学特色的研究 论文
小学三年级英语课堂教学论文
小学英语教学论文 快乐中去学习英语
英语论文 让用英语交流成为小学生的习惯
小学英语教师论文:课堂教学活动
小学英语教学论文 让课堂教学“活”起来
小学英语教学论文 单词教学五个步骤
探索小学英语句子教学法(论文)
小学英语教学论文 如何培养学生的创新精神
英语歌谣:Row your boat 划小船
论文 谈小学英语教学起始阶段兴趣的培养
浅谈体态语在小学英语教学中的应用 论文
少儿英语歌曲:Little Jack Horner 小杰克
论文 小学英语语法教学的三个原则
小学英语论文:运用新情境,提高学生兴趣
如何在小学英语教学中培养学生的创新精神 论文
小学英语课堂教学论文 采用合理的评价手段
小学英语教学论文 课堂教学语言应简单易懂
小学英语单词教学论文
小学英语论文 如何让小学生主动学习英语
论文 小学英语“情趣教学”漫谈
不限 |
英语教案 |
英语课件 |
英语试题 |
不限 |
不限 |
上册 |
下册 |
不限 |