An example of a messenger is a（）.

As oil pipe line connections were broken，（）quantity of oil was caused to spill onto the wharf and into the dock water.

The function of the bypass valve on the self-contained breathing apparatus is to（）.

The exhaust pipe must be gas tight throughout its entire length otherwise（）.

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

The boat is stowed on the davit rather than on a cradle with which type of davit?（）

If a gasoline engine turns over freely but will not start，the cause is generally（）.

An integral part of a blowout preventer that serves as the closing element on an open hole，and whose ends do not fit around the drill pipe but seal against each other and shut off the space below completely is the（）.

The extension of the after part of the keel in a single-screw vessel upon which the stern post rests is called the（）.

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（）.