| |||
非必需元素 |
non-element : 55 phrases in 15 subjects |
Agriculture | 3 |
Aviation | 3 |
Bridge construction | 1 |
Desert science | 1 |
Earth sciences | 1 |
Ecology | 3 |
Electronics | 3 |
Genetics | 2 |
Metallurgy | 5 |
Oil / petroleum | 2 |
Polymers | 1 |
Space | 2 |
Technology | 24 |
Telecommunications | 2 |
Wind Energy | 2 |