What is it called when it is possible to ignite the vapour above the oil?（）

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

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

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

（）is where the crew eat their meals.

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

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

The helm command PORT TWENTY means（）.

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

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