| |||
visible signal | |||
distinguishable signal | |||
visual indication | |||
visual signal | |||
| |||
visible signal |
可见 信号 : 12 phrases in 9 subjects |
Agriculture | 1 |
Air defense | 2 |
Aviation | 1 |
Electronics | 1 |
Information technology | 1 |
Metallurgy | 1 |
Oil / petroleum | 2 |
Technology | 1 |
Telecommunications | 2 |