| |||
| 时间源 | |||
|
time source : 14 phrases in 9 subjects |
| Air defense | 1 |
| Aviation | 2 |
| Computer networks | 1 |
| Earth sciences | 2 |
| Electronics | 1 |
| Geophysics | 1 |
| Oil / petroleum | 1 |
| Technology | 4 |
| Water resources | 1 |
| |||
| 时间源 | |||
|
time source : 14 phrases in 9 subjects |
| Air defense | 1 |
| Aviation | 2 |
| Computer networks | 1 |
| Earth sciences | 2 |
| Electronics | 1 |
| Geophysics | 1 |
| Oil / petroleum | 1 |
| Technology | 4 |
| Water resources | 1 |