| 1 | Oxygen is an important gas. | |
| 2 | He decided to preserve the last breath of air for someone else to use. | |
| 3 | The tissue needs to be supplemented with new blood and oxygen in order to recover. | |
| 4 | Oxygen is necessary for respiration in most living organisms. | |
| 5 | Oxygen therapy is used to treat patients with respiratory disorders or diseases. |