海底隧道

Page21_1, originally uploaded by Raphael Lo.

If you want to know the secret of a cross-harbour tunnel, take a look at this cross-section diagramme. Below the sea level, there are tunnels for vehicles, fish tanks, railway, water tank and you can let some fish out to take a holiday in the sea.
要知道海底隧道的秘密,請看這幅橫切面圖。有行車的通道,地鐵,魚缸和大水缸。