| |||
basic ring; bottom ring | |||
foundation ring; discharge ring | |||
base ring | |||
| |||
discharge ring |
基 础环 : 21 phrases in 10 subjects |
Bridge construction | 1 |
Earth sciences | 1 |
Ecology | 1 |
Electric machinery | 1 |
Electronics | 1 |
Engineering geology | 1 |
Information technology | 1 |
Oil / petroleum | 1 |
Technology | 10 |
United Nations | 3 |