Hashash explains that the immersed-tube design requires largeportions of the tunnel to be built on a dry dock that is floated outinto the water and sunk.
哈沙什解释说，沉管式的设计要求大部分的隧道建筑在干坞上，干坞漂浮并沉没在水里。
2
When the ship was in dock, the dock gates shut to keep the water in.