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environmental level : 23 phrases in 10 subjects |
Apollo-Soyuz | 1 |
Ecology | 4 |
Geophysics | 1 |
Makarov | 3 |
Medical | 4 |
Natural resourses and wildlife conservation | 3 |
Nuclear and fusion power | 1 |
Production | 2 |
United Nations | 3 |
Weapons of mass destruction | 1 |