A.熱水熱網(wǎng) B.一級管網(wǎng) C.地溝管網(wǎng) D.閉式管網(wǎng)
A.10% B.30% C.50% D.70%
A.補焊或蓋壓補焊 B.補麻、補灰 C.兩合揣袖 D.更換