Physics:Chemistry of Life and Death
Oxygen is useful stuff. But 2000 million years ago， you see no oxygen in the atmosphere then， just nasty gases like methane and ammonia. And it wasn't until the first plant life show up and start to photosynthesize that the oxygen began to appear. If oxygen is the basis of life， it is still something of a double-edged sword.
- Added：2006
- Country：Britain
- Duration：30
- Time of update：2011/8/15 16:20:17