Due to lapse of time the risk in these areas to surface navigation is now considered （）than the ordinary risks of navigation，but a very real risk still exists with regard to anchoring，fishing or any form of submarine or seabed activity.

The height of a light is measured from which reference plane?（）

During daylight savings time the meridian used for determining the time is located farther （）.

Conditions for crossing a rough bar are usually best at （）.

At last，the palm trees that fringe the natural harbor of Port Aloahoa come into view on the horizon lit by the setting sun.The meaning of this sentence is that （）.

The Earth’s irregular heating is caused by （）.

In Admiralty Sailing Directions，bands is the word used to indicate（）marking．

The distance between the surface of the water and the tidal datum is the （）.

The distance from the still water level (corrected for tides and storm surge) to the bottom of the hull of a ship is the（）.

AFTER DROPPING THE PILOT means （）.