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

The company should establish and maintain procedures to control all documents and date which are relevant to（）.

Where would you find information about the time of high tide at a specific location on a particular day of the year?（）

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

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