When the wave period and the apparent rolling period are the same（）.

Despite the rising importance and great convenience of the gyrocompass,the magnetic compass still retain its importance because of its（）.

The mean draft of a ship is the draft（）.

According to the relevant regulation, lifeboat should be powered by（）.

Shipboard Emergency Drills must be carried out at least（）on board cargo ship.

Fog is likely to occur when there is little difference between the dew point and the（）.

When steering by autopilot,how often should the steering be checked?（）

Full details of all lights and fog signals are shown on（）.

Bales close to the deckhead should be covered to prevent（）.

Berthing means bringing a vessel to her berth until（）.