净化 系统 : 119 phrases in 17 subjects |
Automobiles | 12 |
Aviation | 2 |
Chemistry | 1 |
Drilling | 1 |
Earth sciences | 1 |
Ecology | 2 |
Electronics | 36 |
Engineering geology | 1 |
Environment | 1 |
Hydroelectric power stations | 1 |
Metallurgy | 14 |
Nuclear and fusion power | 4 |
Oil / petroleum | 3 |
Space | 5 |
Technology | 31 |
United Nations | 1 |
Water resources | 3 |