I then solderedup the top and bottom of the boiler.
当时我焊接起来的顶部和底部锅炉。
2
Once the landings were attached by sealed inserts to the concrete floors, the flights of stairs were soldered by sections on the spot before being hoisted up to 12 meters.
这些构件一旦被植入混凝土平台，台阶的拉索在升到12米前将被分段焊接。
3
Please be careful not to pile up P. W. B. after switches were soldered.