 |
| |||
| nonreturn flap valve | |||
| 止回瓣阀: 4 phrases in 4 subjects |
| Hydroelectric power stations | 1 |
| Metallurgy | 1 |
| Oil / petroleum | 1 |
| Technology | 1 |
|
| |||
| nonreturn flap valve | |||
| 止回瓣阀: 4 phrases in 4 subjects |
| Hydroelectric power stations | 1 |
| Metallurgy | 1 |
| Oil / petroleum | 1 |
| Technology | 1 |