 |
| |||
| 观察纲要 | |||
| observation program: 13 phrases in 4 subjects |
| Aviation | 3 |
| Earth sciences | 7 |
| Electronics | 1 |
| Space | 2 |
The server is undergoing maintenance and the site is working in read-only mode. Please check back later.">Add | The server is undergoing maintenance and the site is working in read-only mode. Please check back later.">Report an error
| Get short URL | Language Selection Tips