自振频率 : 28 phrases in 12 subjects |
Automobiles | 2 |
Aviation | 1 |
Communications | 1 |
Electronics | 5 |
Engineering geology | 2 |
Geophysics | 1 |
Hydroelectric power stations | 2 |
Metallurgy | 1 |
Oil / petroleum | 2 |
Rail transport | 1 |
Technology | 8 |
Telecommunications | 2 |