6. By the end of the next century, a single city may have more than 100 million inhabitants. Eventually there may be cities with more than a billion residents. 

到下个世纪末，ー个城市的人口就可能会超过ー亿。最终，也许会出现人口在十亿以上的大城市。

7. Today, this knowledge allows us to send probes to the farthest reaches of the solar system and to put men an the surface of the moon 一 things that Newton could only have dreamed about.

今天，这种知识使我们能够把探测器送到太阳系的最远处，把人送到月球上。这一切对牛顿来说，只不过是梦想而已。

8. Men have invented such an aeroplane that can hover in the air. This machine is called a helicopter.

人们已经发明了一种能在空中停留的飞机，这种飞机叫做直升飞机。

9. Men have invented such an aeroplane that can hover in the air. This machine is called a helicopter.

人们已经发明了一种能在空中停留的飞机，这种飞机叫做直升飞机。

10. As long as the history of land warfare has been recorded, in each conflict a weapon has been the dominant factor. 

自从有地面战争记载以来，在每一次战争中，武器都一直是决定性的因素。

11. The germ theory of disease made possible the curing of many ills for which no effective treatments had ever before been known.

关于疾病的细菌理论，使得多种过去不能有效治疗的疾病有了治愈的可能。

12. Add some ferric thiocyanide to water and the solution turns blood red.

在水中加些硫氰酸铁，水就变成血红色。

责任编辑：admin