 |
| |||
| 信号钟 | |||
| signal clock: 13 phrases in 8 subjects |
| Air defense | 1 |
| Aviation | 1 |
| Basketball | 1 |
| Information technology | 1 |
| Rail transport | 1 |
| Space | 1 |
| Technology | 6 |
| Telecommunications | 1 |
|
| |||
| 信号钟 | |||
| signal clock: 13 phrases in 8 subjects |
| Air defense | 1 |
| Aviation | 1 |
| Basketball | 1 |
| Information technology | 1 |
| Rail transport | 1 |
| Space | 1 |
| Technology | 6 |
| Telecommunications | 1 |