The helm command PORT TWENTY means（）.

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

A tide is called diurnal when（）.

Which of the following shall not the officers in charge of the navigational watch do?（）

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

（）is where the crew eat their meals.

It is dangerous for vessels without the operational radar（）the estuary.

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

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

（）is on the panel of radar.