 |
| |||
| central switching office; central exchange; central office; district exchange; primary exchange | |||
| main exchange; parent exchange | |||
|
central principal : 13 短语, 5 学科 |
| 一般 | 4 |
| 技术 | 4 |
| 政治 | 1 |
| 机械工程 | 2 |
| 电信 | 2 |
|
| |||
| central switching office; central exchange; central office; district exchange; primary exchange | |||
| main exchange; parent exchange | |||
|
central principal : 13 短语, 5 学科 |
| 一般 | 4 |
| 技术 | 4 |
| 政治 | 1 |
| 机械工程 | 2 |
| 电信 | 2 |