 |
| ecological system: 46 phrases in 17 subjects |
| Astronautics | 9 |
| Aviation | 1 |
| Aviation medicine | 2 |
| Computers | 1 |
| Ecology | 10 |
| Economy | 2 |
| Education | 1 |
| Energy industry | 6 |
| Fishery fishing industry | 1 |
| General | 4 |
| Geography | 1 |
| Law | 1 |
| Medical | 1 |
| Military | 1 |
| Oil and gas | 1 |
| Technology | 2 |
| Weapons of mass destruction | 2 |