Which of the following is not a form of precipitation?（）

Which of the following is not an operation mode of AIS?（）

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

How long are you prohibited to consume alcohol prior to serving as a member of a watch?（）

Before any loading takes place any signs of the previous cargo should do（）.

The circulation around a low pressure center in the Northern Hemisphere is（）.

（）is halfway between the forward and after perpendiculars and is reference point for vessel construction.

（）is on the panel of radar.

（）is where the crew eat their meals.

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