| 1. | The lake is probably more than 30 million years old .
这个湖可能已有三千万年以上的历史。 |
| 2. | It was dated by the potassium-argon method to 1. 8 million years old .
由钾氩法测定其年龄为180万年。 |
| 3. | The site was marshy from about 3. 3 million to 3. 1 million years ago .
这里在大约330万年到310万年前是一个沼泽。 |
| 4. | By this means the age of the earth had been estimated at several hundred million years .
用这个办法推算出地球的年龄是数亿年。 |
| 5. | The oldest sediments cored to date are about 150 million years old .
到目前为止取出的最老沉积物的岩心是大约15亿年以前的生成。 |
| 6. | The rate of subsidence of the basement in geosynclines is more than 12 m, per million years .
地槽基底的下陷速度超过12米百万年。 |
| 7. | The consolidation of the crust can hardly have occured less than 20 or more than 40 million years ago .
地壳的凝固不会少于2000万年，或多于4000万年。 |
| 8. | The quasars cannot shine for longer than a few million years with their present luminosity .
在几百万年以后，类星体将不可能具有他们今天那样的发光度。 |
| 9. | Meteorites have also been analysed, and a few of them appear to be not less than 7, 000 million years old .
有人分析过陨石，其中只有少数陨石的年龄似乎在70亿年以上。 |
| 10. | Throughout most of the 2 million years of human existence on earth, humanity's numbers have been few .
人类生存在地球上已有200万年的历史了，其中大部分时间地球上的人的数量少得可怜。 |
