As the propeller turns，voids are formed on the trailing and leading edges of the propeller blades causing a loss of propulsive efficiency，pitting of the blades，and vibration. These voids are known as（）.

An example of a messenger is a（）.

The rudders are amidships and both screws are going ahead. What will happen if the starboard screw is stopped?（）

All electrical appliances aboard a vessel should be grounded to（）.

The C02 flooding system is actuated by a sequence of steps which are（）.

Limit switches are used on which davits?（）

Cargo pump relief valves are piped to the（）.

In nautical terminology a dog is a（）.

Each cylinder in a two stroke cycle engine experiences combustion（）.

The bypass valve on a self-contained breathing device should be opened if（）.