The tunnel would be well-ventilated (9) tall chimneys were built (10) sea level.
只需建造些高出海面的高高的烟囱，该隧道便会通风良好。
2
Why It's Unique: At 787 feet below sea level, theSeikan Tunnel is the deepest tunnel in the world.
独特之处： 坐落在787英尺的海平面下的青函隧道是世界上最深的隧道。
3
The construction practices of Qinling Tunnel on Xi'an Ankang Railway Lines make the synthetic technical level of tunnel construction in China up to a new stage.